Editing Roger Bacon (section)

==Works==
[[File:Roger Bacon Wellcome M0004484.jpg|thumb|200px|right|A manuscript illustration of Bacon presenting one of his works to the chancellor of the [[University of Paris]]]]
Medieval European philosophy often relied on [[Argument from authority|appeals to the authority]] of [[Church Fathers]] such as [[Augustine of Hippo|St&nbsp;Augustine]], and on works by [[Plato]] and [[Aristotle]] only known at second hand or through Latin translations. By the 13th century, new works and better versions – in [[Arabic]] or in new Latin translations from the Arabic – began to trickle north from [[Al-Andalus|Muslim Spain]]. In Roger Bacon's writings, he upholds Aristotle's calls for the collection of facts before deducing scientific truths, against the practices of his contemporaries, arguing that "thence cometh quiet to the mind".

Bacon also called for reform with regard to [[theology]]. He argued that, rather than training to debate minor philosophical distinctions, theologians should focus their attention primarily on the [[Bible]] itself, learning the languages of its original sources thoroughly. He was fluent in several of these languages and was able to note and bemoan several corruptions of scripture, and of the works of the Greek philosophers that had been mistranslated or misinterpreted by scholars working in Latin. He also argued for the education of theologians in science ("[[natural philosophy]]") and its addition to the [[Medieval university#Course of study|medieval curriculum]].

===''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}}]]

===''Secret of Secrets''===
{{main|Secretum Secretorum}}
Bacon attributed the ''Secret of Secrets'' (''{{lang|la|Secretum Secretorum}}''), the Islamic "Mirror of Princes" ({{langx|ar|Sirr al-ʿasrar}}<!--sic-->), to [[Aristotle]], thinking that he had composed it for [[Alexander the Great]]. Bacon produced an edition of [[Philip of Tripoli]]'s Latin translation, complete with his own introduction and notes; and his writings of the 1260s and 1270s cite it far more than his contemporaries did. This led [[Stewart C. Easton|Easton]]{{sfnp|Easton|1952}} and others, including [[Robert Steele (medievalist)|Robert Steele]],{{sfnp|Williams|1997}} to argue that the text spurred Bacon's own transformation into an experimentalist. (Bacon never described such a decisive impact himself.){{sfnp|Williams|1997}} The dating of Bacon's edition of the ''Secret of Secrets'' is a key piece of evidence in the debate, with those arguing for a greater impact giving it an earlier date;{{sfnp|Williams|1997}} but it certainly influenced the elder Bacon's conception of the political aspects of his work in the sciences.{{sfnp|''Stanford Encyclopedia of Philosophy''|2013|loc=§2}}

===Alchemy===
[[File:Roger Bacon conducting an alchemical experiment in a vaulted Wellcome V0025604.jpg|thumb|200px|alt=J. Nasmyth (1845)|A 19th-century etching of Bacon conducting an alchemical experiment]]
Bacon has been credited with a number of [[alchemy|alchemical]] texts.{{sfnp|Bartlett|2008|p=124}}

The ''Letter on the Secret Workings of Art and Nature and on the Vanity of Magic'' (''{{lang|la|Epistola de Secretis Operibus Artis et Naturae et de Nullitate Magiae}}''),{{sfnp|Brewer|1859|pp=[http://gallica.bnf.fr/ark:/12148/bpt6k50167j/f631.item.zoom 523 ff]}} also known as ''On the Wonderful Powers of Art and Nature'' (''{{lang|la|De Mirabili Potestate Artis et Naturae}}''), a likely-forged letter to an unknown "William of Paris," dismisses practices such as [[necromancy]]{{sfnp|Zambelli|2007|pp=48–49}} but contains most of the alchemical formulae attributed to Bacon,{{sfnp|Bartlett|2008|p=124}} including one for a [[philosopher's stone]]{{sfnp|Newman|1997|pp=328–329}} and another possibly for [[gunpowder]].{{sfnp|Needham|Lu|Wang|1987|pp=48–50}} It also includes several passages about [[history of flight|hypothetical flying machines]] and [[history of submarines|submarines]], attributing their first use to [[Alexander the Great]].{{sfnp|Gray|2011|pp=185–186}} ''On the Vanity of Magic'' or ''The Nullity of Magic'' is a [[debunking]] of esoteric claims in Bacon's time, showing that they could be explained by natural phenomena.{{sfnp|Borlik|2011|p=[https://books.google.com/books?id=c_ShAgAAQBAJ&pg=PA132 132]}}

He wrote on the medicine of [[Galen]], referring to the translations of [[Avicenna]]. He believed that the medicine of Galen belonged to an ancient tradition passed through [[Chaldea|Chaldeans]], [[Greeks]] and [[Arab]]s.<ref>{{cite journal|first1=David Eugene|last1=Smith|author-link1=David Eugene Smith|title=Medicine and Mathematics in the Sixteenth Century|pmc=7927718|pmid= 33943138|journal=Ann Med Hist.|date=July 1, 1917|volume= 1|issue=2|pages=125–140|oclc=12650954}} (here cited p. 126).</ref> Although he provided a negative image of [[Hermes Trismegistus]], his work was influenced by the [[Renaissance]] Hermetic thought{{dubious|date=December 2023}}{{what?|date=December 2023}}.<ref>{{cite journal|first1=George|last1=Molland|url=|title=Roger Bacon and the Hermetic Tradition in Medieval Science|journal=Vivarium|volume=XXXI|issue= 1|year=1993|pages= 140–160|jstor=42569882|publisher=Brill|doi=10.1163/156853493X00123|oclc=812885091|issn=0042-7543}}</ref> Bacon's endorsement of Hermetic philosophy is evident, as his citations of the alchemical literature known as the Secretum Secretorum made several appearances in the Opus Majus. The Secretum Secretorum contains knowledge about the Hermetic [[Emerald Tablet]], which was an integral component of alchemy, thus proving that Bacon's version of alchemy was much less secular, and much more spiritual than once interpreted. The importance of Hermetic philosophy in Bacon's work is also evident through his citations of classic Hermetic literature such as the Corpus Hermeticum. Bacon's citation of the Corpus Hermeticum, which consists of a dialogue between Hermes and the pagan deity [[Asclepius]], proves that Bacon's ideas were much more in line with the spiritual aspects of alchemy rather than the scientific aspects. However, this is somewhat paradoxical as what Bacon was specifically trying to prove in the Opus Majus and subsequent works, was that spirituality and science were the same entity. Bacon believed that by using science, certain aspects of spirituality such as the attainment of "Sapientia" or "Divine Wisdom" could be logically explained using tangible evidence. Bacon's Opus Majus was first and foremost, a compendium of sciences which he believed would facilitate the first step towards "Sapientia". Bacon placed considerable emphasis on alchemy and even went so far as to state that alchemy was the most important science. The reason why Bacon kept the topic of alchemy vague for the most part, is due to the need for secrecy about esoteric topics in England at the time as well as his dedication to remaining in line with the alchemical tradition of speaking in symbols and metaphors.<ref>{{cite book|first1=Victoria |last1=Tobes |url=https://scholarsarchive.library.albany.edu/cgi/viewcontent.cgi?article=1017&context=history_honors|title=Roger Bacon: The Christian, the Alchemist, the Enigma (History Honors Program. 12)|pages=29–30|format=PDF|quote="the Creator may be known through the knowledge of the creature…to whom service may be rendered…in the beauty of morals."|publisher=University at Albany, State University of New York|year=2019|archive-url=https://web.archive.org/web/20200321100704/https://scholarsarchive.library.albany.edu/cgi/viewcontent.cgi?article=1017&context=history_honors|archive-date=March 21, 2020|url-status=live}} (degree thesis)</ref>

===Linguistics===
{{main|Summa Grammatica}}
{{see also|Universal grammar}}
Bacon's early linguistic and logical works are the ''Overview of Grammar'' (''[[Summa Grammatica]]''), ''{{lang|la|Summa de Sophismatibus et Distinctionibus}}'', and the ''{{lang|la|Summulae Dialectices}}'' or ''{{lang|la|Summulae super Totam Logicam}}''.{{sfnp|''Stanford Encyclopedia of Philosophy''|2013|loc=§2}} These are mature but essentially conventional presentations of Oxford and Paris's terminist and pre-[[modistae|modist]] logic and grammar.{{sfnp|''Stanford Encyclopedia of Philosophy''|2013|loc=§2}} His later work in linguistics is much more idiosyncratic, using terminology and addressing questions unique in his era.<ref name=hovd1>{{harvp|Hovdhaugen|1990|p=[https://books.google.com/books?id=8UxAAAAAQBAJ&pg=PA124 121–122]}}.</ref>

In his ''[[Grammatica Graeca|Greek]]'' and ''[[Grammatica Hebraica|Hebrew Grammars]]'' (''{{lang|la|Grammatica Graeca}}'' and ''{{lang|la|Hebraica}}''), in his work "On the Usefulness of Grammar" (Book III of the ''{{lang|la|[[#Opus Majus|Opus Majus]]}}''), and in his ''Compendium of the Study of Philosophy'',<ref name=hovd1/> Bacon stresses the need for scholars to know several languages.<ref name=hovd8/> Europe's vernacular languages are not ignored—he considers them useful for practical purposes such as [[medieval trade|trade]], [[Christian proselytism|proselytism]], and [[government in the High Middle Ages|administration]]—but Bacon is mostly interested in his era's [[languages of science]] and religion: [[Arabic]], [[Greek language|Greek]], [[Hebrew language|Hebrew]] and [[Medieval Latin|Latin]].<ref name=hovd8>{{harvp|Hovdhaugen|1990|p=[https://books.google.com/books?id=8UxAAAAAQBAJ&pg=PA128 128]}}.</ref>

Bacon is less interested in a full practical mastery of the other languages than on a theoretical understanding of their grammatical rules, ensuring that a Latin reader will not misunderstand passages' [[authorial intent|original meaning]].<ref name=hovd8/> For this reason, his treatments of Greek and Hebrew grammar are not isolated works on their topic<ref name=hovd8/> but contrastive grammars treating the aspects which influenced Latin or which were required for properly understanding Latin texts.<ref name=hovd9>{{harvp|Hovdhaugen|1990|p=[https://books.google.com/books?id=8UxAAAAAQBAJ&pg=PA129 129]}}.</ref> He pointedly states, "I want to describe Greek grammar for the benefit of Latin speakers".<ref name=hovd3/>{{refn|group=n|Latin: ''{{lang|la|Cupiens igitur exponere gramaticam grecam ad vtilitatem latinorum}}''.<ref name=hovd3>{{harvp|Hovdhaugen|1990|p=[https://books.google.com/books?id=8UxAAAAAQBAJ&pg=PA123 123]}}.</ref>}} It is likely only this limited sense which was intended by Bacon's boast that he [[Language education|could teach an interested pupil a new language]] within three days.<ref name=hovd9/>{{refn|group=n|It has been claimed that the copies of Bacon's grammars which have survived was not their final form, but [[Eva Hovdhaugen|Hovdhaugen]] considers that—even if that were the case—the final form would have been similar in scope to the surviving texts and mostly focused on improving a Latinate reader's understanding of texts in translation.<ref name=hovd9/>}}

Passages in the ''Overview'' and the Greek grammar have been taken as an early exposition of a [[universal grammar]] underlying all [[human]] [[language]]s.<ref name=lawman>{{harvp|Murphy|1974|p=[https://books.google.com/books?id=8B5z0MiRnJ8C&pg=PA153 153]}}.</ref> The Greek grammar contains the tersest and most famous exposition:<ref name=lawman/>
{{blockquote|Grammar is one and the same in all languages, substantially, though it may vary, accidentally, in each of them.{{refn|[[Edmond Nolan|Nolan]],{{sfnp|Nolan & al.|1902|p=27}} cited in [[James J. Murphy|Murphy]].{{sfnp|Murphy|1974|p=[https://books.google.com/books?id=8B5z0MiRnJ8C&pg=PA154 154]}}}}{{refn|group=n|[[Latin]]: ''{{lang|la|...grammatica vna et eadem est secundum substanciam in omnibus linguis, licet accidentaliter varietur...}}.''<ref name=hovd3/>}}}}
However, Bacon's lack of interest in studying a literal [[grammar]] underlying the languages known to him and his numerous works on linguistics and comparative linguistics has prompted [[Eva Hovdhaugen|Hovdhaugen]] to question the usual literal translation of Bacon's ''{{lang|la|grammatica}}'' in such passages.<ref name=hovd7/> She notes the ambiguity in the Latin term, which could refer variously to the structure of language, to its description, and to the science underlying such descriptions: i.e., [[linguistics]].<ref name=hovd7>{{harvp|Hovdhaugen|1990|p=[https://books.google.com/books?id=8UxAAAAAQBAJ&pg=PA127 127–128]}}.</ref>

===Other works===
[[File:Roger Bacon Wellcome M0004130.jpg|thumb|right|200px|A portrait of Roger Bacon from a 15th-century edition of ''{{lang|la|De Retardatione}}''<ref>MS Bodl. 211.</ref>]]
[[File:Roger Bacon page from book.jpg|right|200px|thumb|The first page of the letter from Bacon to {{nowrap|[[Pope Clement IV|Clement IV]]}} introducing his ''{{lang|la|Opus Tertium}}''{{sfnp|Brewer|1859|loc=[https://books.google.com/books?id=wMUKAAAAYAAJ&pg=PR9-IA6 Plate III]}}]]

Bacon states that his ''Lesser Work'' (''{{lang|la|Opus Minus}}'') and ''Third Work'' (''{{lang|la|Opus Tertium}}'') were originally intended as summaries of the ''{{lang|la|Opus Majus}}'' in case it was lost in transit.{{sfnp|Clegg|2003|p=[https://books.google.com/books?id=IiqeBAAAQBAJ&pg=PT66 66]}} [[Stewart C. Easton|Easton]]'s review of the texts suggests that they became separate works over the course of the laborious process of creating a [[Foul papers|fair copy]] of the ''{{lang|la|Opus Majus}}'', whose half-million words were copied by hand and apparently greatly revised at least once.{{sfnp|Clegg|2003|p=[https://books.google.com/books?id=IiqeBAAAQBAJ&pg=PT67 67]}}

Other works by Bacon include his "Tract on the Multiplication of Species" (''{{lang|la|Tractatus de Multiplicatione Specierum}}''),{{sfnp|Bacon|1897|p=[https://archive.org/stream/opusmajusofroger02bacouoft#page/404/mode/2up 405–552]}} "On Burning Lenses" (''{{lang|de|De Speculis Comburentibus}}''), the ''{{lang|la|Communia Naturalium}}'' and ''{{lang|la|Mathematica}}'', the "Compendium of the Study of Philosophy" and "of Theology" (''{{lang|la|Compendium Studii Philosophiae}}'' and ''{{lang|la|Theologiae}}''), and his ''Computus''.{{sfnp|''Stanford Encyclopedia of Philosophy''|2013|loc=§2}} The "Compendium of the Study of Theology", presumably written in the last years of his life, was an anticlimax: adding nothing new, it is principally devoted to the concerns of the 1260s.

===Apocrypha===
''[[The Mirror of Alchimy]]''<!--sic--> (''{{lang|la|Speculum Alchemiae}}''), a short treatise on the origin and composition of metals, is traditionally credited to Bacon.<ref>{{citation |last=Zwart |first=Hub |author-mask=Zwart |title=Understanding Nature |date=2008 |page=236 }}</ref> It espouses the Arabian theory of [[Mercury (element)|mercury]] and [[Sulfur|sulphur]] forming the other metals, with vague allusions to [[Alchemy|transmutation]]. [[John Maxson Stillman|Stillman]] opined that "there is nothing in it that is characteristic of Roger Bacon's style or ideas, nor that distinguishes it from many unimportant alchemical lucubrations of anonymous writers of the thirteenth to the sixteenth centuries", and [[M. M. Pattison Muir|Muir]] and [[Edmund Oscar von Lippmann|Lippmann]] also considered it a [[Pseudepigrapha|pseudepigraph]].{{sfnp|Stillman|1924|p=271}}

The cryptic [[Voynich manuscript]] has been attributed to Bacon by various sources, including by its first recorded owner,{{sfnp|Newbold & al.|1928}}{{sfnp|Goldstone & al.|2005}}<ref>{{citation |url=https://query.nytimes.com/gst/fullpage.html?res=9C03E4DD103AF933A15751C0A9639C8B63&pagewanted=1 |contribution=The Bacon Code |last=Steele |first=Margaret Farley |author-mask=Steele |date=20 Feb 2005 |title=NY Times }}</ref> but [[history of science|historians of science]] [[Lynn Thorndike]] and [[George Sarton]] dismissed these claims as unsupported,<ref>{{citation |last=Thorndike |first=Lynn |author-mask=Thorndike |author-link=Lynn Thorndike |contribution=Review of ''The Cipher of Roger Bacon'' |title=The American Historical Review |volume=34, No.&nbsp;2 |issue=2 |pages=317–319 |date=Jan 1928 |jstor=1838571 |title-link=The American Historical Review |publisher=Oxford University Press, American Historical Association |doi=10.2307/1838571 }}</ref><ref>{{citation |last=Sarton |first=George |author-mask=Sarton |author-link=George Sarton |contribution=Review of ''The Cipher of Roger Bacon'' |title=Isis |volume=11, No.&nbsp;1 |issue=1 |pages=141–145 |jstor=224770 |date=Sep 1928 |doi=10.1086/346365 |publisher=The University of Chicago Press, The History of Science Society }}</ref><ref>{{citation |last=Foster |first=Benjamin R. |author-mask=Foster |editor-last=Garraty |editor-first=John Arthur |editor2-last=Carnes |editor2-first=Mark Christopher |display-editors=0 |title=American National Biography |contribution=William Romaine Newbold |date=1999 |title-link=American National Biography }}</ref> and the [[vellum]] of the manuscript has since been dated to the 15th century.<ref>{{cite web|title=UA Experts Determine Age of Book 'Nobody Can Read'|url=http://uanews.arizona.edu/story/ua-experts-determine-age-of-book-nobody-can-read|publisher=University of Arizona|access-date=3 December 2015|date=9 February 2011}}</ref>