Editing Aristotle (section)

== Natural philosophy ==
Aristotle's "natural philosophy" spans a wide range of natural phenomena including those now covered by physics, biology and other natural sciences.{{sfn| Wildberg | 2016}} In Aristotle's terminology, "natural philosophy" is a branch of philosophy examining the phenomena of the natural world, and includes fields that would be regarded today as physics, biology and other natural sciences. Aristotle's work encompassed virtually all facets of intellectual inquiry. Aristotle makes philosophy in the broad sense coextensive with reasoning, which he also would describe as "science". However, his use of the term ''science'' carries a different meaning than that covered by the term "scientific method". For Aristotle, "all science (''dianoia'') is either practical, poetical or theoretical" (''Metaphysics'' 1025b25). His practical science includes ethics and politics; his poetical science means the study of fine arts including poetry; his theoretical science covers physics, mathematics and metaphysics.{{sfn|Wildberg|2016}}

=== Physics ===
[[File:Four Classical Elements in Burning Log.svg| thumb | The four [[classical element]]s (fire, air, water, earth) of [[Empedocles]] and Aristotle illustrated with a burning log. The log releases all four elements as it is destroyed.]]
{{Main|Aristotelian physics}}

==== Five elements ====
{{Main|Classical element}}

In his ''[[On Generation and Corruption]]'', Aristotle related each of the four elements proposed earlier by [[Empedocles]], [[Earth (classical element)|earth]], [[Water (classical element)|water]], [[Air (classical element)|air]], and [[Fire (classical element)|fire]], to two of the four sensible qualities, hot, cold, wet, and dry. In the Empedoclean scheme, all matter was made of the four elements, in differing proportions. Aristotle's scheme added the heavenly [[Aether (classical element)|aether]], the divine substance of the [[heavenly spheres]], stars and planets.{{sfn|Lloyd|1968|pages=133–139, 166–169}}

{| class="wikitable"
|+ [[Classical element|Aristotle's elements]]{{sfn|Lloyd|1968|pages=133–139, 166–169}}
! Element !!{{font color|red|Hot}}/{{font color|blue|Cold}} !!{{font color|green|Wet}}/{{font color|brown|Dry}} !! Motion !! Modern [[State of matter|state<br />of matter]]
|-
|'''[[Earth (classical element)|Earth]]'''||{{font color|blue|Cold}}||{{font color|brown|Dry}}||Down||[[Solid]]
|-
|'''[[Water (classical element)|Water]]'''||{{font color|blue|Cold}}||{{font color|green|Wet}}||Down||[[Liquid]]
|-
|'''[[Air (classical element)|Air]]'''||{{font color|red|Hot}}||{{font color|green|Wet}}||Up||[[Gas]]
|-
|'''[[Fire (classical element)|Fire]]'''||{{font color|red|Hot}}||{{font color|brown|Dry}}||Up||[[Plasma (physics)|Plasma]]
|-
|'''[[Aether (classical element)|Aether]]'''||(divine<br />substance)||None||Circular<br />(in heavens)||[[Vacuum]]
|}

==== Motion ====
{{further | History of classical mechanics}}

Aristotle describes two kinds of motion: "violent" or "unnatural motion", such as that of a thrown stone, in the ''Physics'' (254b10), and "natural motion", such as of a falling object, in ''On the Heavens'' (300a20). In violent motion, as soon as the agent stops causing it, the motion stops also: in other words, the natural state of an object is to be at rest,{{sfn| Allain | 2016}}{{efn-ua | Rhett Allain notes that [[Newton's First Law]] is "essentially a direct reply to Aristotle, that the natural state is ''not to change'' motion.{{sfn| Allain | 2016}}}} since Aristotle does not address [[friction]].{{sfn| Drabkin | 1938 | pp=60–84}} With this understanding, it can be observed that, as Aristotle stated, heavy objects (on the ground, say) require more force to make them move; and objects pushed with greater force move faster.{{sfn| Susskind | 2011}}{{efn-ua | Leonard Susskind comments that Aristotle had clearly never gone [[ice skating]] or he would have seen that it takes force to stop an object.{{sfn| Susskind | 2011}}}} This would imply the equation{{sfn| Susskind | 2011}}

:: <math>F=mv</math>,

incorrect in modern physics.{{sfn| Susskind | 2011}}

Natural motion depends on the element concerned: the aether naturally moves in a circle around the heavens,{{efn-ua | For heavenly bodies like the Sun, Moon, and stars, the observed motions are "to a very good approximation" circular around the Earth's centre, (for example, the apparent rotation of the sky because of the rotation of the Earth, and the rotation of the moon around the Earth) as Aristotle stated.{{sfn| Rovelli | 2015 | pp=23–40}}}} while the 4 Empedoclean elements move vertically up (like fire, as is observed) or down (like earth) towards their natural resting places.{{sfn| Rovelli | 2015 | pp=23–40}}{{sfn| Drabkin | 1938 | pp=60–84}}{{efn-ua | Drabkin quotes numerous passages from ''Physics'' and ''On the Heavens'' (''De Caelo'') which state Aristotle's laws of motion.{{sfn| Drabkin | 1938 | pp=60–84}}}}

[[File:Aristotle's laws of motion.svg| thumb | upright=1.5 | Aristotle's laws of motion. In ''[[Physics (Aristotle)|Physics]]'' he states that objects fall at a speed proportional to their weight and inversely proportional to the density of the fluid they are immersed in.{{sfn| Drabkin | 1938 | pp=60–84}} This is a correct approximation for objects in Earth's gravitational field moving in air or water.{{sfn| Rovelli | 2015 | pp=23–40}}]]

In the ''Physics'' (215a25), Aristotle effectively states a quantitative law, that the speed, v, of a falling body is proportional (say, with constant c) to its weight, W, and inversely proportional to the density,{{efn-ua | Drabkin agrees that density is treated quantitatively in this passage, but without a sharp definition of density as weight per unit volume.{{sfn| Drabkin | 1938 | pp=60–84}}}} ρ, of the fluid in which it is falling:;{{sfn| Rovelli | 2015 | pp=23–40}}{{sfn| Drabkin | 1938 | pp=60–84}}

:: <math>v=c\frac{W}{\rho}</math>

Aristotle implies that in a [[vacuum]] the speed of fall would become infinite, and concludes from this apparent absurdity that a vacuum is not possible.{{sfn| Rovelli | 2015 | pp=23–40}}{{sfn| Drabkin | 1938 | pp=60–84}} Opinions have varied on whether Aristotle intended to state quantitative laws. Henri Carteron held the "extreme view"{{sfn| Drabkin | 1938 | pp=60–84}} that Aristotle's concept of force was basically qualitative,{{sfn| Carteron | 1923 | pages=1–32 and passim}} but other authors reject this.{{sfn| Drabkin | 1938 | pp=60–84}}

[[Archimedes]] corrected Aristotle's theory that bodies move towards their natural resting places; metal boats can float if they [[Archimedes' principle|displace enough water]]; floating depends in Archimedes' scheme on the mass and volume of the object, not, as Aristotle thought, its elementary composition.{{sfn| Rovelli | 2015 | pp=23–40}}

Aristotle's writings on motion remained influential until the [[early modern]] period. [[John Philoponus]] (in [[late antiquity]]) and [[Galileo]] (in the early modern period) are said to have shown by experiment that Aristotle's claim that a heavier object falls faster than a lighter object is incorrect.{{sfn| Wildberg | 2016}} A contrary opinion is given by [[Carlo Rovelli]], who argues that Aristotle's physics of motion is correct within its domain of validity, that of objects in the [[Earth]]'s gravitational field immersed in a fluid such as air. In this system, heavy bodies in steady fall indeed travel faster than light ones (whether friction is ignored, or not{{sfn| Rovelli | 2015 | pp=23–40}}), and they do fall more slowly in a denser medium.{{sfn| Susskind | 2011}}{{efn-ua | Philoponus and Galileo correctly objected that for the transient phase (still increasing in speed) with heavy objects falling a short distance, the law does not apply: Galileo used balls on a short incline to show this. Rovelli notes that "Two heavy balls with the same shape and different weight do fall at different speeds from an aeroplane, confirming Aristotle's theory, not Galileo's."{{sfn| Rovelli | 2015 | pp=23–40}}}}

Newton's "forced" motion corresponds to Aristotle's "violent" motion with its external agent, but Aristotle's assumption that the agent's effect stops immediately it stops acting (e.g., the ball leaves the thrower's hand) has awkward consequences: he has to suppose that surrounding fluid helps to push the ball along to make it continue to rise even though the hand is no longer acting on it, resulting in the Medieval [[theory of impetus]].{{sfn| Rovelli | 2015 | pp=23–40}}

==== Four causes ====

{{main|Four causes}}

[[File:Aristotle's Four Causes of a Table.svg| thumb | upright=1.5 | Aristotle argued by analogy with woodwork that a thing takes its form from [[four causes]]: in the case of a table, the wood used ([[material cause]]), its design ([[formal cause]]), the tools and techniques used ([[efficient cause]]), and its decorative or practical purpose ([[final cause]]).{{sfn| Leroi | 2015 | pages=88–90}}]]

Aristotle suggested that the reason for anything coming about can be attributed to four different types of simultaneously active factors. His term ''aitia'' is traditionally translated as "cause", but it does not always refer to temporal sequence; it might be better translated as "explanation", but the traditional rendering will be used here.{{sfn| Lloyd | 1996 | pages=96–100, 106–107}}{{sfn| Hankinson | 1998 | page=159}}
* [[Material cause]] describes the material out of which something is composed. Thus the material cause of a table is wood. It is not about action. It does not mean that one domino knocks over another domino.{{sfn| Lloyd | 1996 | pages=96–100, 106–107}}
* The [[formal cause]] is its form, i.e., the arrangement of that matter. It tells one what a thing is, that a thing is determined by its definition, form or pattern. It embraces the account of causes in terms of principles or general laws, as the whole is the cause of its parts, a relationship known as whole-part causation. Plainly put, the formal cause is the idea in the mind of the sculptor that brings the sculpture into being. A simple example is the mental image or idea that allows an artist, architect, or engineer to create a drawing.{{sfn| Lloyd | 1996 | pages=96–100, 106–107}}
* The [[efficient cause]] is "the primary source", or that from which the change under consideration proceeds. It identifies 'what makes of what is made and what causes change of what is changed' and so suggests all sorts of agents, non-living or living, acting as the sources of change or movement or rest. This covers modern definitions of "cause" as either the agent or agency or particular events or states of affairs. In the case of two dominoes, when the first is knocked over it causes the second to fall.{{sfn| Lloyd | 1996 | pages=96–100, 106–107}} In the case of an animal, this agency is a combination of [[developmental biology|how it develops from the egg]], and [[physiology|how its body functions]].{{sfn| Leroi | 2015 | pages=91–92, 369–373}}
* The [[final cause]] (''telos'') is its purpose, the reason why it exists or is done, including both purposeful and instrumental actions. The final cause is the purpose or function that something is supposed to serve. This covers modern ideas of motivating causes, such as volition.{{sfn| Lloyd | 1996 | pages=96–100, 106–107}} In the case of living things, it implies [[adaptation]] to a particular way of life.{{sfn| Leroi | 2015 | pages=91–92, 369–373}}

==== Optics ====

Aristotle was aware of Pythagorean optics.<ref>Burnyeat, Myles F. "[https://www.cambridge.org/core/journals/science-in-context/article/abs/archytas-and-optics/BDBF3868CEF7004C16547836D66A4F24 Archytas and optics]". ''Science in Context'' 18.1 (2005): pp. 35-53.</ref> He used optics in his ''Meteorology'', treating it as a science.<ref>{{cite journal |last=Berryman |first=Sylvia |title='It Makes No Difference': Optics and Natural Philosophy in Late Antiquity |journal=Apeiron |volume=45 |issue=3 |date=2012 |doi=10.1515/apeiron-2012-0001 |url=https://www.degruyter.com/document/doi/10.1515/apeiron-2012-0001/html}}</ref> He viewed optics as stating the laws of sight, thus combining what is now treated as physics and biology.<ref>Cantor, Geoffrey N. "Physical optics". ''Companion to the History of Modern Science''. Routledge, 2006. pp. 627-638.</ref> The process of seeing involved the movement of a visible form from the thing seen through the air (or other medium) to the eye, where the form comes to rest. Aristotle does not analyse the nature of this movement; he does not anticipate [[geometrical optics]].<ref>Matthen, Mohan. "[https://philpapers.org/archive/MATITE-3.docx Is the eye like what it sees? A critique of Aristotle on sensing by assimilation]". ''Vivarium'' 57.3-4 (2019): pp. 268-292.</ref>

==== Chance and spontaneity ====

{{further|Accident (philosophy)}}

According to Aristotle, spontaneity and chance are causes of some things, distinguishable from other types of cause such as simple necessity. Chance as an incidental cause lies in the realm of [[Accident (philosophy)|accidental things]], "from what is spontaneous". There is also more a specific kind of chance, which Aristotle names "luck", that only applies to people's moral choices.{{sfn|Physics|p=2.6}}{{sfn|Miller|1973|pp=204–213}}

=== Astronomy ===
{{further | History of astronomy}}

In [[astronomy]], Aristotle refuted [[Democritus]]'s claim that the [[Milky Way]] was made up of "those stars which are shaded by the earth from the sun's rays," pointing out partly correctly that if "the size of the sun is greater than that of the earth and the distance of the stars from the earth many times greater than that of the sun, then... the sun shines on all the stars and the earth screens none of them."{{sfn| Meteorology | p=1. 8}} He also wrote descriptions of comets, including the [[Great Comet of 371 BC]].{{sfn| Meteorology}}

=== Geology and natural sciences ===
{{further | History of geology}}
[[File:Aerial image of Stromboli (view from the northeast).jpg| thumb | Aristotle noted that the ground level of the [[Aeolian islands]] changed before a [[volcanic eruption]].]]
Aristotle was one of the first people to record any [[geological]] observations. He stated that [[Uniformitarianism|geological change]] was too slow to be observed in one person's lifetime.{{sfn| Moore | 1956 | page=13}}{{sfn| Meteorology | p=Book 1, Part 14}}
The geologist [[Charles Lyell]] noted that Aristotle described such change, including "lakes that had dried up" and "deserts that had become watered by rivers", giving as examples the growth of the [[Nile delta]] since the time of [[Homer]], and "the upheaving of one of the [[Aeolian islands]], previous to a [[volcanic eruption]]."'{{sfn| Lyell | 1832 | page=17}}

''Meteorologica'' lends its name to the modern study of meteorology, but its modern usage diverges from the content of Aristotle's ancient treatise on [[meteors]]. The ancient Greeks did use the term for a range of atmospheric phenomena, but also for [[earthquakes]] and volcanic eruptions. Aristotle proposed that the cause of earthquakes was a gas or vapor (''anathymiaseis'') that was trapped inside the earth and trying to escape, following other Greek authors [[Anaxagoras]], [[Empedocles]] and [[Democritus]].<ref>{{cite book |last1=Udias |first1=Agustin |last2=Buforn |first2=Elisa |title=Principles of Seismology |date=2018 |publisher=Cambridge University Press |page=1}}</ref>

Aristotle also made many observations about the hydrologic cycle. For example, he made some of the earliest observations about desalination: he observed early – and correctly – that when seawater is heated, freshwater evaporates and that the oceans are then replenished by the cycle of rainfall and river runoff ("I have proved by experiment that salt water evaporated forms fresh and the vapor does not when it condenses condense into sea water again.")<ref>{{cite book |last=Aristotle |translator-last=Lee |translator-first=H. D. P. |title=Meteorologica, Chapter II |year=1952 |publisher=[[Harvard University Press]] |location=Cambridge, Massachusetts |page=156 |edition=Loeb Classical Library |url=http://archive.org/details/L397AristotleMeteorologica |access-date=22 January 2021}}</ref>

=== Biology ===
{{Main|Aristotle's biology}}
[[File:Tremoctopus violaceus5.jpg| thumb | upright=0.8 | Among many pioneering zoological observations, Aristotle described the reproductive [[hectocotyl arm]] of the [[octopus]] (bottom left).]]

==== Empirical research ====

Aristotle was the first person to study biology systematically,{{sfn|Leroi|2015|page=7}} and biology forms a large part of his writings. He spent two years observing and describing the zoology of [[Lesbos]] and the surrounding seas, including in particular the Pyrrha lagoon in the centre of Lesbos.{{sfn|Leroi|2015|page=14}}{{sfn| Thompson | 1910 | page=Prefatory Note}} His data in ''[[History of Animals]]'', ''[[Generation of Animals]]'', ''[[Movement of Animals]]'', and ''[[Parts of Animals]]'' are from his own observations,<ref>{{Cite news |url=https://www.independent.co.uk/arts-entertainment/books/reviews/darwins-ghosts-by-rebecca-stott-7808310.html |title=Darwin's Ghosts, By Rebecca Stott |work=The Independent (UK) |date=2 June 2012 |access-date=19 June 2012}}</ref> statements by knowledgeable people such as beekeepers and fishermen, and accounts by travellers.{{sfn|Leroi|2015|pages=196, 248}} His apparent emphasis on animals rather than plants is a historical accident: his works on [[botany]] have been lost, but two books on plants by his pupil Theophrastus have survived.{{sfn|Day|2013|pp=5805–5816}}

Aristotle reports on sea-life from observation on Lesbos and the catches of fishermen. He describes the [[catfish]], [[electric ray]], and [[frogfish]], as well as [[cephalopod]]s such as the [[octopus]] and [[paper nautilus]]. His description of the [[hectocotyl arm]] of cephalopods, used in sexual reproduction, was widely disbelieved until the 19th century.{{sfn|Leroi|2015|pages=66–74, 137}} He gives accurate descriptions of the four-chambered stomachs of [[ruminant]]s,{{sfn|Leroi|2015|pages=118–119}} and of the [[ovoviviparous]] embryological development of the [[hound shark]].{{sfn|Leroi|2015|page=73}}

He notes that an animal's structure is well matched to function so the [[heron]] has a long neck, long legs, and a sharp spear-like beak, whereas [[duck]]s have short legs and webbed feet.{{sfn|Leroi|2015|pages=135–136}} [[Charles Darwin|Darwin]], too, noted such differences, but unlike Aristotle used the data to come to the theory of [[evolution]].{{sfn|Leroi|2015|page=206}} Aristotle's writings can seem to imply evolution, but Aristotle saw mutations or [[Hybridisation (biology)|hybridizations]] as rare accidents, distinct from natural causes. He was thus critical of Empedocles's theory of a "survival of the fittest" origin of living things and their organs, and ridiculed the idea that accidents could lead to orderly results.{{sfn|Sedley|2007|page=189}} In modern terms, he nowhere says that different species can have a [[common ancestor]], that one kind can [[speciation|change into another]], or that kinds can become [[extinct]].{{sfn|Leroi|2015|page=273}}

==== Scientific style ====

[[File:Two of Aristotle's Growth Laws.svg| thumb | left | upright=1.2 | Aristotle inferred growth laws from his observations on animals, including that [[brood size]] decreases with body mass, whereas [[gestation]] period increases.]]

Aristotle did not do experiments in the modern sense.{{sfn|Taylor|1922|page=42}} He made observations, or at most investigative procedures like dissection.{{sfn|Leroi|2015|pages=361–365}} In ''Generation of Animals'', he opens a fertilized hen's egg to see the embryo's heart beating inside.{{sfn|Leroi|2011}}{{sfn|Leroi|2015|pages=197–200}}

Instead, he systematically gathered data, discovering patterns common to whole groups of animals, and inferring possible causal explanations from these.{{sfn|Leroi|2015|pages=365–368}}{{sfn|Taylor|1922|page=49}} This style is common in modern biology when large amounts of data become available in a new field, such as [[genomics]]. This sets out testable hypotheses and constructs a narrative explanation of what is observed. In this sense, [[Aristotle's biology]] is scientific.{{sfn|Leroi|2015|pages=365–368}}

From his data, Aristotle inferred [[biological rules|rules]] relating the life-history features of live-bearing tetrapods (terrestrial placental mammals) that he studied. He correctly predicted thatb rood size decreases with body mass; that [[Life expectancy|lifespan]] increases with [[gestation period]] and with body mass, and that [[fecundity]] decreases with lifespan.{{sfn|Leroi|2015|page=408}}{{Clear}}

==== Classification of living things ====

{{further|Scala naturae}}

[[File:FMIB 46109 Foetal Picked Dogfish, with the ovum attached (no label).jpeg|thumb|Aristotle recorded that the [[embryo]] (fetus pictured) of [[Mustelus canis|a dogfish]] was attached by a cord to a kind of placenta (the [[yolk sac]]), like a higher animal; this formed an exception to the linear scale from highest to lowest.{{sfn|Leroi|2015|pages=72–74}}]]

Aristotle distinguished about 500 [[animal]] species,{{sfn|Bergstrom|Dugatkin|2012|page=35}}{{sfn|Rhodes|1974|page=7}} arranging them in a nonreligious graded [[scala naturae|scale of perfection]], with man at the top. The highest gave [[viviparity|live birth]] to hot and wet creatures, the lowest laid cold, dry mineral-like eggs.{{sfn|Mayr|1982|pages=201–202}}{{sfn|Lovejoy|1976}} He grouped what a zoologist would call [[vertebrate]]s as "animals with blood", and [[invertebrate]]s as "animals without blood". Those with blood were divided into live-bearing ([[mammal]]s), and egg-laying ([[bird]]s, [[reptile]]s, [[fish]]). Those without blood were insects, crustacea and hard-shelled [[mollusc]]s. He recognised that animals did not exactly fit onto a scale, and noted exceptions, such as that sharks had a [[placenta]]. To a biologist, the explanation<!--Leroi |p= 113--> is [[convergent evolution]].{{sfn|Leroi|2015|pages=111–119}} Philosophers of science have concluded that Aristotle was not interested in taxonomy,<ref>{{cite book |last=Lennox |first=James G. |title=Aristotle's Philosophy of Biology: Studies in the Origins of Life Science |date=2001 |publisher=[[Cambridge University Press]] |location=Cambridge |isbn=0-521-65976-0 |pages=346}}</ref><ref>{{cite journal |last1=Sandford |first1=Stella |title=From Aristotle to Contemporary Biological Classification: What Kind of Category is "Sex"? |journal=Redescriptions: Political Thought, Conceptual History and Feminist Theory |date=3 December 2019 |volume=22 |issue=1 |pages=4–17 |doi=10.33134/rds.314 |s2cid=210140121 |issn=2308-0914 |doi-access=free}}</ref> but zoologists think otherwise.<ref>{{cite journal |last1=Voultsiadou |first1=Eleni |last2=Gerovasileiou |first2=Vasilis |last3=Vandepitte |first3=Leen |last4=Ganias |first4=Kostas |last5=Arvanitidis |first5=Christos |title=Aristotle's scientific contributions to the classification, nomenclature and distribution of marine organisms |journal=Mediterranean Marine Science |year=2017 |volume=18 |issue=3 |pages=468–478 |doi=10.12681/mms.13874 |url=https://doi.org/10.12681/mms.13874 |issn=1791-6763}}</ref><ref>{{cite journal |last1=von Lieven |first1=Alexander Fürst |last2=Humar |first2=Marcel |title=A Cladistic Analysis of Aristotle's Animal Groups in the "Historia animalium" |journal=History and Philosophy of the Life Sciences |year=2008 |volume=30 |issue=2 |pages=227–262 |jstor=23334371 |pmid=19203017 |url=https://www.jstor.org/stable/23334371 |issn=0391-9714}}</ref><ref>{{cite book |last1=Laurin |first1=Michel |title=The Advent of PhyloCode: The Continuing Evolution of Biological Nomenclature (section 1.1.3) |date=3 August 2023 |publisher=CRC Press |location=Boca Raton, Fl |isbn=978-1-00-091257-9 |pages=xv + 209 |url=https://books.google.com/books?id=-P3BEAAAQBAJ&pg=PA1}}</ref><!-- He believed that purposive final causes guided all natural processes; this [[teleological]] view justified his observed data as an expression of formal design.{{sfn|Mason|1979|pp=43–44}}-->

{|class="wikitable"
|+ Aristotle's ''[[Scala naturae]]'' (highest to lowest)
! Group !! Examples<br />(given by Aristotle) !! Blood !! Legs !! Souls<br />(Rational,<br />Sensitive,<br />Vegetative) !! Qualities<br />({{font color|red|Hot}}–{{font color|blue|Cold}},<br />{{font color|green|Wet}}–{{font color|brown|Dry}})
|-
|Man||Man||with&nbsp;blood||2 legs||R, S, V||{{font color|red|Hot}}, {{font color|green|Wet}}
|-
|[[Mammal|Live-bearing tetrapods]]||Cat, [[hare]]||with&nbsp;blood||4 legs||S, V||{{font color|red|Hot}}, {{font color|green|Wet}}
|-
|[[Cetaceans]]||[[Dolphin]], [[whale]]||with&nbsp;blood||none||S, V||{{font color|red|Hot}}, {{font color|green|Wet}}
|-
|[[Birds]]||[[Bee-eater]], [[nightjar]]||with&nbsp;blood||2 legs||S, V||{{font color|red|Hot}}, {{font color|green|Wet}}, except {{font color|brown|Dry}} eggs
|-
|[[Reptile|Egg-laying tetrapods]]||[[Chameleon]], [[crocodile]]||with&nbsp;blood||4 legs||S, V||{{font color|blue|Cold}}, {{font color|green|Wet}} except scales, eggs
|-
|[[Snakes]]||Water snake, [[Ottoman viper]]||with&nbsp;blood||none||S, V||{{font color|blue|Cold}}, {{font color|green|Wet}} except scales, eggs
|-
|Egg-laying [[fish]]es||[[Sea bass]], [[Sparisoma cretense|parrotfish]]||with&nbsp;blood||none||S, V||{{font color|blue|Cold}}, {{font color|green|Wet}}, including eggs
|-
|(Among the egg-laying fishes):<br />placental [[selachian]]s||[[Shark]], [[Skate (fish)|skate]]||with&nbsp;blood||none||S, V||{{font color|blue|Cold}}, {{font color|green|Wet}}, but [[placenta]] like tetrapods
|-
|[[Crustaceans]]||[[Shrimp]], [[crab]]||without||many legs||S, V||{{font color|blue|Cold}}, {{font color|green|Wet}} except shell
|-
|[[Cephalopods]]||[[Squid]], [[octopus]]||without||tentacles||S, V||{{font color|blue|Cold}}, {{font color|green|Wet}}
|-
|[[Mollusc|Hard-shelled animals]]||[[Cockle (bivalve)|Cockle]], [[Charonia variegata|trumpet snail]]||without||none||S, V||{{font color|blue|Cold}}, {{font color|brown|Dry}} (mineral shell)
|-
|Larva-bearing insects||[[Ant]], [[cicada]]||without||6 legs||S, V||{{font color|blue|Cold}}, {{font color|brown|Dry}}
|-
|[[Spontaneous generation|Spontaneously generating]]||[[Sponges]], [[worm]]s||without||none||S, V||{{font color|blue|Cold}}, {{font color|green|Wet}} or {{font color|brown|Dry}}, from earth
|-
|[[Plants]]||[[Fig]]||without||none||V||{{font color|blue|Cold}}, {{font color|brown|Dry}}
|-
|[[Mineral]]s||Iron||without||none||none||{{font color|blue|Cold}}, {{font color|brown|Dry}}
|}

=== Psychology ===

==== Soul ====

{{further | On the Soul}}

[[File:Aristotelian Soul.png| thumb | upright=1.5 | Aristotle proposed a three-part [[Soul#Aristotle|structure for souls]] of plants, animals, and humans, making humans unique in having all three types of soul.]]

Aristotle's [[psychology]], in his treatise ''[[On the Soul]]'' ({{tlit|grc|peri psychēs}}), posits three kinds of [[soul]] ({{tlit|grc|psyches}}): the vegetative, sensitive, and rational. Humans have all three. The vegetative soul is concerned with growth and nourishment. The sensitive soul experiences sensations and movement. The uniquely human, rational soul receives forms of things and compares them using the {{tlit|grc|[[Nous#Aristotle|nous]]}} (intellect) and {{tlit|grc|logos}} (reason).{{sfn|Leroi|2015|pp=156–163}}

For Aristotle, the soul is the [[Hylomorphism#Body–soul hylomorphism|form]] of a living being. Because all beings are composites of form and matter, the form of living beings is that which endows them with what is specific to living beings, e.g. the ability to initiate movement.{{sfn|Shields|2016}} In contrast to earlier philosophers, but in accordance with the Egyptians, he placed the rational soul in the heart.{{sfn|Mason|1979|p=45}} Aristotle distinguished sensation and thought, unlike previous philosophers except for [[Alcmaeon of Croton|Alcmaeon]].{{sfn|Guthrie|2010|p=348}}

In ''On the Soul'', Aristotle criticizes Plato's theory of the soul and develops his own in response. Firstly he criticises Plato's ''Timaeus'' which holds the soul takes up space and can come into physical contact with bodies.{{sfn|On the Soul|loc=I.3 406b26-407a10}} 20th-century scholarship held that Aristotle had here misinterpreted Plato.<ref>For instance, Ross, William D. ed. 1961. ''Aristotle: De Anima''. Oxford: Oxford University Press, page 189.</ref> Aristotle also argued that Plato's view of reincarnation entails that a soul and its body can be mis-matched; in principle, Aristotle alleges, any soul can go with any body, according to Plato's theory.{{sfn|On the Soul|loc= I.3 407b14–27}}

==== Memory ====

According to Aristotle in ''On the Soul'', memory is the ability to hold a perceived experience in the mind and to distinguish between the internal "appearance" and a past occurrence.{{sfn|Bloch|2007|p=12}} A memory is a mental picture ([[wikt:phantasm|phantasm]]) that can be recovered. An impression is left on a semi-fluid bodily organ that undergoes changes in order to make a memory. A memory occurs when [[stimulus (psychology)|stimuli]] such as sights or sounds are so complex that the nervous system cannot receive them all at once. These changes are the same as those involved in sensation, {{Avoid wrap|'[[common sense]]'}}, and thinking.{{sfn|Bloch|2007|p=61}}{{sfn|Carruthers|2007|p=16}}

Aristotle uses the term 'memory' for the actual retaining of an experience in the impression that develops from sensation, and for the intellectual anxiety that comes with the impression because it is formed at a particular time and processing specific contents. Memory is of the past, prediction is of the future, and sensation is of the present. Retrieval of impressions cannot be performed suddenly. A transitional channel is needed and located in past experiences, both for previous experience and present experience.{{sfn|Bloch|2007|p=25}}

Because Aristotle believes people perceive all kinds of sense perceptions as impressions, people continually weave together new impressions of experiences. To search for impressions, people search memory itself.{{sfn|Warren|1921|p=30}} Within memory, if an experience is offered instead of a specific memory, that person will reject this experience until they find what they are looking for. Recollection occurs when a retrieved experience naturally follows another. If the chain of "images" is needed, one memory stimulates the next. When people recall experiences, they stimulate certain previous experiences until they reach the one that is needed.{{sfn|Warren|1921|p=25}} Recollection is thus the self-directed activity of retrieving information stored in a memory impression.{{sfn|Carruthers|2007|p=19}} Only humans can remember impressions of intellectual activity, such as numbers and words. Animals that have perception of time can retrieve memories of their past observations. Remembering involves only perception of the things remembered and of the time passed.{{sfn|Warren|1921|p=296}}

[[File:Aristotle Senses Perception Memory Dreams Action.svg| thumb | upright=1.5 | Senses, perception, memory, dreams, action in Aristotle's psychology. Impressions are stored in the [[sensorium]] (the heart), linked by his [[laws of association]] (similarity, contrast, and [[Contiguity (psychology)|contiguity]]).]]

Aristotle believed the chain of thought that achieves recollection of impressions was connected systematically in relationships such as similarity, contrast, and [[Contiguity (psychology)|contiguity]], described in his [[laws of association]]. Aristotle believed that past experiences are hidden within the mind. A force operates to awaken the hidden material to bring up the actual experience. Association is the power innate in a mental state, which operates upon the unexpressed remains of former experiences, allowing them to be recalled.{{sfn|Warren|1921|p=259}}{{sfn|Sorabji|2006|p=54}}

==== Dreams ====

{{further|Dream#Other}}

Aristotle describes sleep in ''On Sleep and Wakefulness''.{{sfn|Holowchak|1996|pp=405–423}} It is a result of overuse of the senses{{sfn|Shute|1941|pp=115–118}} or of digestion,{{sfn|Holowchak|1996|pp=405–23}} and is vital to the body.{{sfn|Shute|1941|pp=115–118}} While a person is asleep, the critical activities, which include thinking, sensing, recalling and remembering, do not function. Since a person cannot sense during sleep, they cannot have desire. However, the senses work during sleep,{{sfn|Shute|1941|pp=115–118}} albeit differently.{{sfn|Holowchak|1996|pp=405–423}}

Dreams do not involve sensing a stimulus. Sensation is involved, but in an altered manner.{{sfn|Shute|1941|pp=115–118}} Aristotle explains that when a person stares at a moving stimulus such as the waves in a body of water, and then looks away, the next thing they look at appears to have a wavelike motion. When a person perceives a stimulus and it is no longer the focus of their attention, it leaves an impression.{{sfn|Holowchak|1996|pp=405–423}} When the body is awake, a person constantly encounters new stimuli and so the impressions of previous stimuli are ignored.{{sfn|Shute|1941|pp=115–118}} However, during sleep the impressions made throughout the day are noticed, free of distractions.{{sfn|Holowchak|1996|pp=405–423}} So, dreams result from these lasting impressions. Since impressions are all that are left, dreams do not resemble waking experience.{{sfn|Modrak|2009|pp=169–181}} During sleep, a person is in an altered state of mind, like a person who is overtaken by strong feelings. For example, a person who has a strong infatuation with someone may begin to think they see that person everywhere. Since a person sleeping is in a suggestible state and unable to make judgements, they become easily deceived by what appears in their dreams, like the infatuated person.{{sfn|Holowchak|1996|pp=405–423}} This leads them to believe the dream is real, even when the dreams are absurd.{{sfn|Holowchak|1996|pp=405–423}} In ''De Anima'' iii 3, Aristotle ascribes the ability to create, to store, and to recall images to the faculty of imagination, ''phantasia''.{{sfn|Shields|2016}}

One component of Aristotle's theory disagrees with previously held beliefs. He claimed that dreams are not foretelling and not sent by a divine being. Aristotle reasoned that instances in which dreams resemble future events are simply coincidences.{{sfn|Webb|1990|pp=174–184}} Any sensory experience perceived while a person is asleep, such as actually hearing a door close, does not qualify as part of a dream. Images of dreams must be a result of lasting impressions of waking sensory experiences.{{sfn|Modrak|2009|pp=169–181}}