Medieval European philosophy often relied on
appeals to the authority of
Church Fathers such as
St 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
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 curriculum.
Opus Majus studies by Bacon Bacon's 1267
Greater Work, the '
, 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" ('), "The Affinity of Philosophy with Theology" ('
), "On the Usefulness of Grammar" ('), "The Usefulness of Mathematics in Physics" ('
), "On Experimental Knowledge" ('), and "A Philosophy of Morality" (''''). It was not intended as a complete work but as a "persuasive preamble" ('
), 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. 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 ' has been lost),
alchemy,
agriculture (inclusive of
botany and
zoology),
medicine, and "
experimental science", a
philosophy of science that would guide the others. The section on geography was allegedly originally ornamented with a
map based on ancient and Arabic computations of longitude and latitude, but has since been lost. His (mistaken) arguments supporting the idea that dry land formed the larger proportion of the globe were apparently similar to those which later guided
Columbus. His proposal to drop one day every 125 years and to cease the observance of fixed
equinoxes and
solstices and, through Alhazen (
Ibn al-Haytham), on
Ibn Sahl's work on
dioptrics.
Gunpowder was made possible", an image from ''
Bill Nye's Comic History of England'' A passage in the '
and another in the ' are usually taken as the first European descriptions of a mixture containing the essential ingredients of
gunpowder.
Partington and others have come to the conclusion that Bacon most likely witnessed at least one demonstration of
Chinese firecrackers, possibly obtained by Franciscans—including Bacon's friend
William of Rubruck—who visited the
Mongol Empire during this period. The most telling passage reads: 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. At the beginning of the 20th century,
Henry William Lovett Hime of the
Royal Artillery published the theory that Bacon's ''
contained a cryptogram giving a recipe for the gunpowder he witnessed. The theory was criticised by Thorndike in a 1915 letter to Science'' and several books, a position joined by
Muir,
John Maxson Stillman,
Steele, and
Sarton.
Needham et al. concurred with these earlier critics that the additional passage did not originate with Bacon and further showed that the proportions supposedly deciphered (a 7:5:5 ratio of
saltpetre to
charcoal to
sulphur) as not even useful for firecrackers, burning slowly with a great deal of smoke and failing to ignite inside a gun barrel. The ~41%
nitrate content is too low to have explosive properties.
Secret of Secrets Bacon attributed the
Secret of Secrets (''''), the Islamic "Mirror of Princes" (), 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
Easton and others, including
Robert Steele, to argue that the text spurred Bacon's own transformation into an experimentalist. (Bacon never described such a decisive impact himself.) 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; but it certainly influenced the elder Bacon's conception of the political aspects of his work in the sciences.
Alchemy Bacon has been credited with a number of
alchemical texts. The
Letter on the Secret Workings of Art and Nature and on the Vanity of Magic (''
), also known as On the Wonderful Powers of Art and Nature
(''), a likely-forged letter to an unknown "William of Paris", dismisses practices such as
necromancy but contains most of the alchemical formulae attributed to Bacon, including one for a
philosopher's stone and another possibly for
gunpowder. It also includes several passages about
hypothetical flying machines and
submarines, attributing their first use to
Alexander the Great.
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. 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
Chaldeans,
Greeks and
Arabs. Although he provided a negative image of
Hermes Trismegistus, his work was influenced by Hermetic thought. 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.
Linguistics Bacon's early linguistic and logical works are the
Overview of Grammar (
Summa Grammatica), '
, and the ' or ''''. These are mature but essentially conventional presentations of Oxford and Paris's terminist and pre-
modist logic and grammar. His later work in linguistics is much more idiosyncratic, using terminology and addressing questions unique in his era. In his
Greek and
Hebrew Grammars ('
and '), in his work "On the Usefulness of Grammar" (Book III of the ''
), and in his Compendium of the Study of Philosophy'', 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'
original meaning. He pointedly states, "I want to describe Greek grammar for the benefit of Latin speakers". The Greek grammar contains the tersest and most famous exposition:
Other works Bacon states that his
Lesser Work (''
) and Third Work'' ('
) were originally intended as summaries of the ' in case it was lost in transit.
Easton's review of the texts suggests that they became separate works over the course of the laborious process of creating a
fair copy of the '''', whose half-million words were copied by hand and apparently greatly revised at least once. Other works by Bacon include his "Tract on the Multiplication of Species" ('
), "On Burning Lenses" ('), the '
and ', the "Compendium of the Study of Philosophy" and "of Theology" ('
and '), and his
Computus. 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 (''''), a short treatise on the origin and composition of metals, is traditionally credited to Bacon. It espouses the Arabian theory of
mercury and
sulphur forming the other metals, with vague allusions to
transmutation.
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
Muir and
Lippmann also considered it a
pseudepigraph. The cryptic
Voynich manuscript has been attributed to Bacon by various sources, including by its first recorded owner, but
historians of science Lynn Thorndike and
George Sarton dismissed these claims as unsupported, and the
vellum of the manuscript has since been dated to the 15th century. ==Legacy==