{{Short description|1267 treatise by Roger Bacon}}
{{italic title}}
[[File:Bacon - Opus maius, 1750 - 4325246.tif|thumb|''Opus maius'', 1750 edition]]
[[File:Roger Bacon-1.jpg|thumb|First page of a 1750 edition of {{Lang|la|Opus majus}}]]
The '''{{Lang|la|Opus Majus}}''' ([[Latin]] for "Greater Work") is the most important work of [[Roger Bacon]]. It was written in [[Medieval Latin]], at the request of [[Pope Clement IV]], to explain the work that Bacon had undertaken. The 878-page treatise ranges over all aspects of natural science, from grammar and logic to mathematics, physics, and philosophy. Bacon sent his work to the Pope in 1267.[{{Lang|la|Opus Majus}} in year 1267 was accompanied by a letter of dedication to the Pope. ] It was followed later the same year by a smaller second work, his ''[[Opus Minus]]'', which was intended as an abstract or summary of the longer work, followed shortly by a third work, ''[[Opus Tertium]]'', as a preliminary introduction to the other two.
==Contents==
The {{Lang|la|Opus Majus}} is divided into seven parts:
#Part one considers the obstacles to real wisdom and truth, classifying the causes of error (''offendicula'') into four categories: following a weak or unreliable authority, custom, the ignorance of others, and concealing one's own ignorance by pretended knowledge.
#Part two considers the relationship between [[philosophy]] and [[theology]], concluding that theology (and particularly [[Holy Scripture]]) is the foundation of all sciences.
#Part three contains a study of Biblical [[language]]s: [[Latin]], [[Ancient Greek|Greek]], [[Hebrew]], and [[Arabic]], as a knowledge of language and grammar is necessary to understand revealed wisdom.
#Part four contains a study of [[Mathematics]]: As part of the study, he vividly drew out the flaws in the [[Julian Calendar]], proposing to drop a day every 125 years from 325 CE ([[First Council of Nicaea|Council of Nicaea]]). He also noted the shifting of the [[Equinox]]es to the [[Solstice]]s.[David Ewing Duncan, ''The Calendar'', 2011, pp. 3–5.]
#Part five contains a study of [[Optics]]: The study of optics in part five seems to draw on the works of the Arab writers [[Al-Kindi|Kindi]] and [[Alhazen]], including a discussion of the [[physiology]] of [[eyesight]], the [[anatomy]] of the [[human eye|eye]] and the [[human brain|brain]], and considers [[light]], distance, position, and size, direct vision, [[reflection (physics)|reflected]] vision, and [[refraction]], [[mirror]]s and [[lens (optics)|lenses]].
#Part six, ''De scientia experimentalis'', a study of [[Experimental Science]]: It includes a review of [[alchemy]], the creation of gunpowder and of the positions and sizes of the [[celestial bodies]], and anticipates later [[invention]]s, such as [[microscope]]s, [[telescope]]s, [[spectacle]]s, [[flying machine]]s, [[hydraulic]]s and [[steam ship]]s. The [[occult]] overtones of this section reflect Bacon's interest in [[Magic (paranormal)|magic]], which he also wrote about in ''De secretis operibus artis et naturae, et de nullitate magiae''. It was a major influence on [[John Dee]]'s theory of ''Archemastrie''.[{{cite book|last1=Clulee|first1=Nicholas H.|last2=Vickers|first2=Brian|editor1-first=Brian|editor1-last=Vickers|title=Occult and scientific mentalities in the Renaissance|chapter=At the crossroads of magic and science: John Dee's Archemastrie|year=1984|page=59|doi=10.1017/CBO9780511572999.003|isbn=9780511572999}}]
#Part seven considers moral philosophy and [[ethics]].
Historian Amanda Power emphasizes that this major work cannot be usefully read exclusively in the context of the history of science and philosophy while forgetting to consider Bacon's religious commitment to the [[Franciscan Order]]. "''His Opus maius was a plea for reform addressed to the supreme [[Pope|spiritual head of the Christian faith]], written against a background of [[Apocalypse|apocalyptic]] expectation and informed by the driving concerns of the friars. It was designed to improve training for [[missionary|missionaries]] and to provide new skills to be employed in the defence of the Christian world against the enmity of non-Christians and of the [[Antichrist]]''".[(p. 692) {{cite journal
| author = Power, Amanda.
| year = 2006
| title = A Mirror for Every Age: The Reputation of Roger Bacon
| journal = The English Historical Review
| volume = 121
| issue = 492
| pages = 657–692
| doi = 10.1093/ehr/cel102
}}][[Image:Roger Bacon optics01.jpg|thumb|right|Bacon's [[optic]] studies, from {{Lang|la|Opus Majus}}]]
==Publication history==
An incomplete version of Bacon's {{Lang|la|Opus Majus}} was published by [[William Bowyer (printer)|William Bowyer]] in [[London]] in 1733. It was edited by [[Samuel Jebb]] from a manuscript at [[Trinity College, Cambridge]] which omitted the seventh part.
==References==
{{reflist}}
==Sources==
*[https://web.archive.org/web/20060907231554/http://www2.nd.edu/Departments/Maritain/etext/hwp218.htm A History of Western Philosophy Vol. II] by Ralph McInerny from the Jacques Maritain Center, [[University of Notre Dame]]
*[https://www.newadvent.org/cathen/13111b.htm Roger Bacon] from the [[Catholic Encyclopedia]]
*[https://books.google.com/books?id=wMUKAAAAYAAJ ''Fr. Rogeri Bacon Opera quaedam hactenus Inedita'', Vol. 1] at Google Books. Contains the ''Opus Tertium'', ''Opus Minus'', and ''Compendium Philosophiae''.
==External links==
[[File:Roger Bacon-2.jpg|left|thumb|239x239px|1750 edition of {{Lang|la|Opus majus}}]]
* [https://archive.org/details/opusmajusrogerb04bridgoog {{Lang|la|Opus Majus}}, Volume I] in the Internet Archive – original text in Latin (omitting Part IV), ed. by John Henry Bridges, 1897.
* [https://archive.org/details/opusmajusrogerb01bridgoog {{Lang|la|Opus Majus}}, Volume I] in the Internet Archive – original text in Latin (including [https://archive.org/stream/opusmajusrogerb01bridgoog#page/n293/mode/2up Part IV]), ed. by John Henry Bridges, 1900.
* [https://archive.org/details/opusmajusofroger02bacouoft {{Lang|la|Opus Majus}}, Volume II] in the Internet Archive – original text in Latin, ed. by John Henry Bridges, 1897.
* [https://books.google.com/books?id=OYbmqiwIK5YC {{Lang|la|Opus Majus}}, Volume I] at Google Books – English trans. by Robert Belle Burke, 1928.
* [https://archive.org/details/opusmajusofroger002065mbp {{Lang|la|Opus Majus}}, Volume II] in the Internet Archive – English trans. by Robert Belle Burke, 1962.
{{Authority control}}
[[Category:Works by Roger Bacon]]
[[Category:1267 books]]
[[Category:British literature]]
[[Category:13th-century books in Latin]]
[[Category:Medieval philosophical literature]]