Editing Roger Bacon (section)

===''Opus Majus''===
[[File:Roger Bacon optics01.jpg|thumb|200px|[[Optics|Optic]] studies by Bacon]]
{{main|Opus Majus}}
Bacon's 1267 ''Greater Work'', the ''{{lang|la|[[Opus Majus]]}}'',{{refn|group=n|In his works, Bacon also refers to it as his "primary writing" (''{{lang|la|scriptum principale}}'').{{sfnp|Clegg|2003|p=[https://books.google.com/books?id=IiqeBAAAQBAJ&pg=PT64 64]}}}} contains treatments of [[mathematics]], [[optics]], [[alchemy]], and [[astronomy]], including theories on the positions and sizes of the [[celestial bodies]]. It is divided into seven sections: "The Four General Causes of Human Ignorance" (''{{lang|la|Causae Erroris}}''),<ref name="baconI1">{{harvp|Bacon|1897|loc=[https://archive.org/stream/opusmajusofroger01baco Vol.&nbsp;I], [https://archive.org/stream/opusmajusofroger01baco#page/n197/mode/2up Pt.&nbsp;I]}} & [[#{{harvid|Bridges|1900}}|(1900)]], [https://archive.org/stream/b24975655_0003 Vol.&nbsp;III], [https://archive.org/stream/b24975655_0003#page/n19/mode/2up Pt.&nbsp;I].</ref> "The Affinity of Philosophy with Theology" (''{{lang|la|Philosophiae cum Theologia Affinitas}}''),<ref name="baconI2">{{harvp|Bacon|1897|loc=[https://archive.org/stream/opusmajusofroger01baco Vol.&nbsp;I], [https://archive.org/stream/opusmajusofroger01baco#page/32/mode/2up Pt.&nbsp;II]}} & [[#{{harvid|Bridges|1900}}|(1900)]], [https://archive.org/stream/b24975655_0003 Vol.&nbsp;III], [https://archive.org/stream/b24975655_0003#page/36/mode/2up Pt.&nbsp;II].</ref> "On the Usefulness of Grammar" (''{{lang|la|De Utilitate Grammaticae}}''),<ref name="baconI3">{{harvp|Bacon|1897|loc=[https://archive.org/stream/opusmajusofroger01baco Vol.&nbsp;I], [https://archive.org/stream/opusmajusofroger01baco#page/66/mode/2up Pt.&nbsp;III]}} & [[#{{harvid|Bridges|1900}}|(1900)]], [https://archive.org/stream/b24975655_0003 Vol.&nbsp;III], [https://archive.org/stream/b24975655_0003#page/80/mode/2up Pt.&nbsp;III].</ref> "The Usefulness of Mathematics in Physics" (''{{lang|la|Mathematicae in Physicis Utilitas}}''),<ref name=baconI4/> "[[#Optics|On the Science of Perspective]]" (''{{lang|la|De Scientia Perspectivae}}''),<ref name=baconII5>{{harvp|Bacon|1897|loc=[https://archive.org/stream/opusmajusofroger02bacouoft Vol.&nbsp;II], [https://archive.org/stream/opusmajusofroger02bacouoft#page/n7/mode/2up Pt.&nbsp;V] }}</ref> "On Experimental Knowledge" (''{{lang|la|De Scientia Experimentali}}''),<ref name=baconII6>{{harvp|Bacon|1897|loc=[https://archive.org/stream/opusmajusofroger02bacouoft Vol.&nbsp;II], [https://archive.org/stream/opusmajusofroger02bacouoft#page/166/mode/2up Pt.&nbsp;VI] }}</ref> and "A Philosophy of Morality" (''{{lang|la|Moralis Philosophia}}'').<ref name=baconII7>{{harvp|Bacon|1897|loc=[https://archive.org/stream/opusmajusofroger02bacouoft Vol.&nbsp;II], [https://archive.org/stream/opusmajusofroger02bacouoft#page/222/mode/2up Pt.&nbsp;VII] }}</ref>

It was not intended as a complete work but as a "persuasive preamble" (''{{lang|la|persuasio praeambula}}''), an enormous proposal for a reform of the [[medieval university]] curriculum and the establishment of a kind of library or encyclopedia, bringing in experts to compose a collection of definitive texts on these subjects.{{sfnp|Clegg|2003|p=[https://books.google.com/books?id=IiqeBAAAQBAJ&pg=PT66 66]}} The new subjects were to be "perspective" (i.e., [[optics]]), "astronomy" (inclusive of [[astronomy]] proper, [[astrology]], and the [[geography]] necessary to use them), "weights" (likely some treatment of [[mechanics]] but this section of the ''{{lang|la|Opus Majus}}'' has been lost), [[alchemy]], [[agriculture]] (inclusive of [[botany]] and [[zoology]]), [[medicine]], and "[[experiment]]al science", a [[philosophy of science]] that would guide the others.{{sfnp|Clegg|2003|p=[https://books.google.com/books?id=IiqeBAAAQBAJ&pg=PT66 66]}} The section on geography was allegedly originally ornamented with a [[history of cartography|map]] based on ancient and Arabic computations of longitude and latitude, but has since been lost.<ref name=worthy>{{harvp|''Worthies''|1828|pp=[https://books.google.com/books?id=QjhkAAAAcAAJ&pg=PA45 45–46]}}</ref> His (mistaken) arguments supporting the idea that dry land formed the larger proportion of the globe were apparently similar to those which later guided [[Christopher Columbus|Columbus]].<ref name=worthy/>

In this work Bacon criticises his contemporaries [[Alexander of Hales]] and [[Albertus Magnus]], who were held in high repute despite having only acquired their knowledge of [[Aristotle]] at second hand during their preaching careers.{{sfn|Hackett (1997), "Classification"|pp=49–52}}{{sfnp|Hackett|1980}} Albert was received at Paris as an authority equal to Aristotle, [[Avicenna]] and [[Averroes]],{{sfnp|Easton|1952|pp=210–219}} a situation Bacon decried: "never in the world [had] such monstrosity occurred before."{{sfnp|LeMay|1997|pp=40–41}}

In Part I of the ''Opus Majus'' Bacon recognises some philosophers as the ''Sapientes'', or gifted few, and saw their knowledge in philosophy and theology as superior to the ''vulgus philosophantium'', or common herd of philosophers. He held Islamic thinkers between 1210 and 1265 in especially high regard calling them "both philosophers and sacred writers" and defended the integration of philosophy from apostate philosopher of the Islamic world into Christian learning.{{sfnp|Hackett|2011|pp=151–166}}<gallery>
File:Roger Bacon-2.jpg|alt=|Spine of a 1750 edition of ''Opus majus''
File:Bacon - Opus maius, 1750 - 4325246.tif|alt=|Title page of 1750 edition of ''Opus majus''
File:Roger Bacon-1.jpg|alt=|First page of 1750 edition of ''Opus majus''
</gallery>

====Calendrical reform====
{{hatnote|Main: [[Calendrical reform#Julian and Gregorian reforms|Calendrical reform]] and [[Gregorian calendar#Gregorian reform|Gregorian calendar]]}}
In Part IV of the ''{{lang|la|Opus Majus}}'', Bacon proposed a [[Calendar reform|calendrical reform]] similar to the later [[Gregorian calendar#Gregorian reform|system]] introduced in 1582 under [[Pope Gregory XIII]].<ref name=baconI4/> Drawing on [[Ancient Greek astronomy|ancient Greek]] and [[Astronomy in the medieval Islamic world|medieval Islamic]] astronomy recently introduced to western Europe via Spain, Bacon continued the work of [[Robert Grosseteste]] and criticised the then-current [[Julian calendar]] as "intolerable, horrible, and laughable".

It had become apparent that [[Eudoxus of Cnidus|Eudoxus]] and [[Sosigenes of Alexandria|Sosigenes]]'s assumption of a year of 365¼ days was, over the course of centuries, too inexact. Bacon charged that this meant the [[computus|computation of Easter]] had shifted forward by 9 days since the [[First Council of Nicaea]] in 325.<ref name=dunkin>{{citation |last=Duncan |first=David Ewing |author-mask=Duncan |title=The Calendar |date=2011 |pages=1–2 }}</ref> His proposal to drop one day every 125 years<ref name=baconI4>{{harvp|Bacon|1897|loc=[https://archive.org/details/opusmajusrogerb01bridgoog Vol.&nbsp;I], [https://archive.org/stream/opusmajusrogerb01bridgoog#page/n293/mode/2up Pt.&nbsp;IV] }}</ref>{{sfnp|North|1983|pp=75, 82–84}} and to cease the observance of fixed [[equinox]]es and [[solstice]]s<ref name=dunkin/> was not acted upon following the death of [[Pope Clement IV]] in 1268. The eventual [[Gregorian calendar]] drops one day from the first three centuries in each set of 400 years.

====Optics====
[[File:Optics from Roger Bacon's De multiplicatone specierum.jpg|200px|thumb|right|Bacon's diagram of light being refracted by a spherical container of water]]
{{see also|History of optics}}
In Part V of the ''{{lang|la|[[Opus Majus]]}}'', Bacon discusses [[visual system|physiology of eyesight]] and the anatomy of the [[human eye|eye]] and the [[human brain|brain]], considering [[light]], distance, position, and size, direct and [[reflection (physics)|reflected]] vision, [[refraction]], [[mirror]]s, and [[lens (optics)|lenses]].<ref name=baconII5/> His treatment was primarily oriented by the Latin translation of [[Ibn al-Haytham|Alhazen]]'s ''[[Book of Optics]]''. He also draws heavily on [[Eugene of Palermo]]'s Latin translation of the Arabic translation of [[Claudius Ptolemy|Ptolemy]]'s ''[[Optics (Ptolemy)|Optics]]''; on [[Robert Grosseteste]]'s work based on [[Al-Kindi]]'s ''[[Optics (Al-Kindi)|Optics]]'';{{sfnp|Ackerman|1978|p=119}}<ref>{{citation |author=Ptolemy |title=Optics |publisher=(Smith trans.) |url=https://books.google.com/books?id=mhLVHR5QAQkC |date=1996 |page=[https://books.google.com/books?id=mhLVHR5QAQkC&pg=PA58 58] |author-link=Claudius Ptolemy |isbn=9780871698629 }}</ref> and, through Alhazen ([[Ibn al-Haytham]]), on [[Ibn Sahl (mathematician)|Ibn Sahl]]'s work on [[dioptrics]].{{sfnp|El-Bizri|2005}}

====Gunpowder====
[[File:137-ROGER BACON DISCOVERS GUNPOWDER.jpg|thumb|right|200px|"Roger Bacon discovers gunpowder", "whereby [[Guy Fawkes]] was made possible",<ref>{{citation |last=Nye |first=Bill |author-link=Edgar Wilson Nye |display-authors=0 |url=https://archive.org/details/billnyescomichis00nyebrich |title=Bill Nye's Comic History of England |date=1896 |page=[https://archive.org/stream/billnyescomichis00nyebrich#page/136/mode/2up 136] |publisher=Chicago, Thompson and Thomas }}</ref> an image from ''[[Edgar Wilson Nye|Bill Nye]]'s Comic History of England''<ref>{{citation |last=Nye |first=Bill |author-link=Edgar Wilson Nye |display-authors=0 |url=https://archive.org/details/billnyescomichis00nyebrich |title=Bill Nye's Comic History of England |date=1896 |page=[https://archive.org/stream/billnyescomichis00nyebrich#page/136/mode/2up 137] |publisher=Chicago, Thompson and Thomas }}</ref>]]
A passage in the ''{{lang|la|Opus Majus}}'' and another in the ''{{lang|la|Opus Tertium}}'' are usually taken as the first European descriptions of a mixture containing the essential ingredients of [[gunpowder]]. [[J. R. Partington|Partington]] and others have come to the conclusion that Bacon most likely witnessed at least one demonstration of [[Yuan dynasty|Chinese]] [[firecracker]]s, possibly obtained by Franciscans—including Bacon's friend [[William of Rubruck]]—who visited the [[Mongol Empire]] during this period.{{sfnp|Needham|Lu|Wang|1987|pp=48–50}}{{refn|group=n|"Europeans were prompted by all this to take a closer interest in happenings far to the east. Four years after the invasion of 1241, the pope sent an ambassador to the Great Khan's capital in Mongolia. Other travellers followed later, of whom the most interesting was [[William of Rubruck]] (or Ruysbroek). He returned in 1257, and in the following year there are reports of experiments with gunpowder and rockets at Cologne. Then a friend of William of Rubruck, Roger Bacon, gave the first account of gunpowder and its use in fireworks to be written in Europe. A form of gunpowder had been known in China since before AD 900, and as mentioned earlier... Much of this knowledge had reached the Islamic countries by then, and the saltpetre used in making gunpowder there was sometimes referred to, significantly, as 'Chinese snow'."{{sfnp|Pacey|1991|p=[https://books.google.com/books?id=X7e8rHL1lf4C&pg=PA45 45]}}}} The most telling passage reads:
<blockquote>We have an example of these things (that act on the senses) in [the sound and fire of] that children's toy which is made in many [diverse] parts of the world; i.e. a device no bigger than one's thumb. From the violence of that salt called saltpetre [together with sulphur and willow charcoal, combined into a powder] so horrible a sound is made by the bursting of a thing so small, no more than a bit of parchment [containing it], that we find [the ear assaulted by a noise] exceeding the roar of strong thunder, and a flash brighter than the most brilliant lightning.{{sfnp|Needham|Lu|Wang|1987|pp=48–50}} </blockquote>

At the beginning of the 20th century, [[Henry William Lovett Hime]] of the [[Royal Artillery]] published the theory that Bacon's ''{{lang|la|Epistola}}'' contained a [[cryptogram]] giving a recipe for the gunpowder he witnessed.<ref>{{cite EB1911 |last=Hodgkinson |first=William Richard Eaton |wstitle=Gunpowder |mode=cs2}}</ref> The theory was criticised by [[Lynn Thorndike|Thorndike]] in a 1915 letter to ''[[Science (journal)|Science]]''{{sfnp|Thorndike|1915}} and several books, a position joined by [[M. M. Pattison Muir|Muir]],{{sfnp|Stillman|1924|p=202}} [[John Maxson Stillman]],{{sfnp|Stillman|1924|p=202}} [[Robert Steele (medievalist)|Steele]],{{sfnp|Steele|1928}} and [[George Sarton|Sarton]].{{sfnp|Sarton|1948|p=958}} [[Joseph Needham|Needham]] et al. concurred with these earlier critics that the additional passage did not originate with Bacon{{sfnp|Needham|Lu|Wang|1987|pp=48–50}} and further showed that the proportions supposedly deciphered (a 7:5:5 ratio of [[Niter|saltpetre]] to [[charcoal]] to [[Sulfur|sulphur]]) as not even useful for firecrackers, burning slowly with a great deal of smoke and failing to ignite inside a gun barrel.{{sfnp|Needham|Lu|Wang|1987|loc=Vol.&nbsp;V, Pt.&nbsp;7, p.&nbsp;358}} The ~41% [[nitrate]] content is too low to have explosive properties.{{sfnp|Hall|1999|p=xxiv}}

[[File:Friar Bacon.png|thumb|left|200px|Friar Bacon in his study{{sfnp|Baldwin|1905|p=64}}]]