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date: 07 December 2023

Bacon [Bakun], Rogerfree

(c. 1214–1292?)

Bacon [Bakun], Rogerfree

(c. 1214–1292?)
  • George Molland

Bacon [Bakun], Roger (c. 1214–1292?), philosopher and Franciscan friar, is by inference from his later career usually assigned a birth date about 1214, and from early traditions it seems that he came from the south-west of England, perhaps near Ilchester in Somerset.

Early life and academic activities

Bacon studied and probably lectured on arts in Oxford, and then lectured at Paris, where he was a pioneer in teaching Aristotle's natural philosophy. The assertion that he was in Paris by 1236 rests on the very dubious ascription to him of a work De retardatione accidentium senectutum, but he was certainly there by 1245. He was also there in 1251, but a question mark hangs over the intervening years. This arises largely from a reorientation of intellectual outlook which he himself fairly clearly dates at some twenty years earlier than works that he was writing c.1267. 'In the twenty years in which I have laboured specially at the study of wisdom, disregarding the crowd's approach, I have spent more than two thousand pounds on these matters' (Opus tertium, ed. Brewer, 59). In this view his early Aristotelian works deriving from his Paris lectures may be seen as representative of the ‘crowd's approach’, and, although early in date, they do not seem especially remarkable. His new approach may loosely be described as more ‘scientifically’ and technologically oriented, and was strongly influenced by Robert Grosseteste and the Franciscan school at Oxford, especially Adam Marsh, and to a lesser extent Thomas Wallensis, but a question remains as to how exactly he received this influence.

Grosseteste was lecturer to the Franciscans at Oxford from 1229 to 1235, when he became bishop of Lincoln, but for various reasons it is implausible to date much acquaintanceship to this period. Another possibility is to deny that Bacon knew Grosseteste at all, except perhaps for having heard the odd sermon. This may be a little extreme, and does not solve the problem of when he became acquainted with Adam Marsh (whom he certainly knew) and, possibly, Thomas Wallensis. Thomas was lecturer to the Oxford Franciscans from about 1240 to 1247, when he departed to become bishop of St David's, and was succeeded by Adam Marsh, who was also a regent master in theology from 1247 to 1250. Taking all these facts into consideration, there is much to be said for the hypothesis that Bacon returned to Oxford about 1247, in time to have come to know, albeit briefly, Thomas Wallensis, and to have attended Adam Marsh's theological lectures. Grosseteste was by that time bishop of Lincoln, but Oxford was in his diocese and he was friendly with Adam Marsh. It therefore seems quite likely that Bacon would at least have been introduced to him, although A. G. Little's suggestion that he became Grosseteste's assistant, and that one of Grosseteste's works was influenced by him, seems improbable.

It is often assumed that another important cause of Bacon's reorientation was the important pseudo-Aristotelian work, Secretum secretorum, which he believed to be by Aristotle himself. This takes the form of a long letter on kingship addressed to Aristotle's erstwhile pupil Alexander the Great, and has as a strong theme the extreme usefulness of philosophy, of various sciences (including those that would now be called pseudo-sciences), and of medicine. This theme was especially important to Bacon in his new orientation, and from at least 1267 he cites the work with great frequency. He also prepared an edition of it, which included an introductory treatise by himself together with a series of glosses. Since Robert Steele's edition (1920) it has been conventional to date the glosses to the 1250s and the introduction to about 1270. However, a study by S. P. Williams has made a strong case for dating both the introduction and the glosses to about 1270 or later. This weakens the case for its being an especially important factor in bringing about his ‘conversion’ to a new way of approaching knowledge, but at least it was to provide strong reinforcement.

Bacon as Franciscan; the works for the pope

Another important event in Bacon's career that can only be dated tentatively is his entry into the Franciscan order; this has plausibly been put at 1257. Bacon's vocation is unexpected, for his likeness to St Francis was minimal: once again the influence of Adam Marsh and other Englishmen must be suspected. This in turn makes it probable that the event occurred in England, and renders less appealing J. Hackett's otherwise interesting conjecture that Bacon remained in Paris for most of the 1240s and 1250s. It may be accounted unfortunate for him that at roughly the same time Bonaventure became master-general of the order, a man who had a very different spirituality from Bacon's (with, for instance, far greater emphasis on prayer and contemplation). Whether or not it was from a truculent attitude which made it seem advisable to keep him under closer supervision, Bacon was soon back in Paris for a period of some ten years at least, during which time resentment against his superiors may well have induced hypochondria. Nevertheless he managed in this period to make contact with Guy Foulquois, who had formerly been a lawyer and military man, but by 1261 was a cardinal, and in 1264 became Pope Clement IV. Before this Guy had shown interest in Bacon's schemes and asked for his writings, a request that was repeated as a command after his elevation:

Truly, in order that what you intend should be more evident to us, we will and command you as instructed by apostolic letters that, notwithstanding the contrary instruction of any prelate or any regulation of your order, you do not fail to send to us as quickly as possible and in a fair hand the work which, when we were established in a lesser position, we asked you to communicate to our beloved son Raymond de Laon, and that by your words you should make clear to us what remedies seem to you should be applied to those things that you have lately intimated as the occasion of such great danger, and that you do this without delay as secretly as possible.

Opus tertium, ed. Brewer, 1

Because of constraints on writing that had been imposed on the Franciscan order to stop the spread of possibly heretical apocalyptic tracts, and perhaps for other reasons, Bacon had done relatively little writing over the past ten years, and, as he was later to protest to the pope, he had been speaking of works to be produced and not of those already written.

However, a papal command could not be ignored, and Bacon commenced a flurry of activity. The exact details have caused much dispute, and the following account must be to a degree conjectural. What is certain is that it brought about Bacon's most famous work, the Opus maius. This was divided into seven parts, and was aimed at promoting in summary form (albeit at some length) a wide expanse, although not the whole gamut, of natural knowledge. Part 1 treated the causes of human ignorance; part 2, the relation of the other sciences to theology; part 3, grammar and the power of languages; part 4, mathematics (including astronomy and astrology); part 5, optics (perspectiva); part 6, 'experimental science'; part 7, moral philosophy. It seems most likely that this was immediately dispatched to Rome, but then Bacon contracted three worries: the work could be lost in transit; it might be too long for a busy pope to read; some things had been omitted that should have been included. He accordingly started on another work, the Opus minus, to summarize and supplement the larger work. This, it may be surmised, was dispatched to the pope under the care of a special courier known simply as John. This young man, who came from a poor background, had been one of Bacon's favourite pupils, on whom he had tested his educational theories, and whom he had imbued with his own views as to the proper way to approach natural philosophy. It is not certain what happened to John in later life, but quite probably he remained in Rome for some time after this commission. A similar concern that had led Bacon to produce the Opus minus now led him to work on the considerably longer Opus tertium. This may never have been properly revised to Bacon's satisfaction, and was quite probably never sent to the pope, who died in 1268 without leaving any known record of how he reacted to Bacon's ideas. The editorial state of these three works, as of many others in the corpus, is unsatisfactory, but is steadily improving.

Later years

Bacon did not give up writing with the death of Clement IV, but he seems to have become more and more disillusioned and infuriated with what he saw as the increasing corruption of knowledge. His efforts were directed mainly towards a great systematic treatise, in comparison with which the Opus maius had been (because of the shortness of time available) a mere summary. Scholars often refer to this projected writing as the Scriptum principale, but the evidence suggests that Bacon used this term generically rather than as the title of a specific work. More probably he saw the work as entitled Compendium studii philosophiae or Compendium studii theologiae. A fragment with the former title, which can be dated to 1272, was published in the nineteenth century by Brewer, and one with the latter title, datable to 1292, was published by Maloney in 1988. Other fragments, both published and unpublished, were clearly also intended as parts of the grand synthesis.

The evidence strongly suggests that Bacon was back in Oxford about 1270, and he may have spent much of the rest of his life in England. About 1278 there perhaps occurred one of the most controversial episodes in Bacon's career, for it is reported in the Chronica XXIV generalium, a work compiled some 100 years later, that in that year the master-general of the Franciscans, Girolamo da Ascoli, 'condemned and disapproved the teaching of Brother Roger Bacon, Englishman, Doctor of Sacred Theology, as containing certain suspect novelties, on account of which the said Roger was condemned to be imprisoned' (Crowley, 67). A somewhat earlier, but garbled, report says that for alchemical reasons Bacon was imprisoned and later released by Raimondo Gaufredi. Gaufredi did become master-general of the Franciscans in 1289, and did release many prisoners, especially in Italy and those of the spiritual or ‘left wing’ of the order, but notwithstanding many scholarly speculations, there is little evidence that Bacon belonged to this camp.

Because of the tenuous nature of the evidence some scholars have rejected the view that Bacon was imprisoned at all, but on the whole it seems reasonable to suppose that he was placed under some form of restraint, and this for two principal reasons. The first is that by his habitually expressed contempt for many intellectuals of his time, including prominent Dominicans and Franciscans, he was bound to have been highly unpopular in many quarters. The second is that in 1277 the bishop of Paris had produced a famous condemnation of 219 propositions that were not to be maintained (which was soon followed by a much shorter list from the Dominican archbishop of Canterbury, Robert Kilwardby). Bacon's supposed imprisonment was an internal Franciscan matter, but still these condemnations could have provided his superiors with a heaven-sent opportunity for indicting him. For instance, it would have been hard to defend him against the charge of maintaining 'That by diverse signs of the heaven are signified diverse conditions in men as regards both spiritual gifts and temporal things' (Denifle and Chatelain, 1.551). If he was released by the order of Raimondo Gaufredi, this could well have been about 1290, and his last datable writing can be assigned to 1292. Tradition avers that he died in June of that year, and that he was buried in Oxford.

Bacon's view of knowledge

Bacon's intellectual schemes were heavily conditioned by his view of how knowledge had developed. Drawing on sources such as Josephus and Augustine, he held that the plenitude of philosophy had been revealed to the ancient patriarchs and prophets near the beginning of time. For various understandable reasons, its transmission to later ages was accompanied by notable deteriorations and corruptions, and reforms had continually been necessary, often by means of special divine illuminations. By his time there had been three particularly great restorers of knowledge, who significantly came from three distinct cultural and religious traditions: Solomon, Aristotle, Avicenna. The time was obviously ripe for a Christian renewal, and it seems fairly clear that Bacon saw himself as the potential provider of this, although, especially later in life, he emphasized the need for co-operative endeavours.

The ways to reform were manifold, but the means, as he stressed to the pope, were heavily dependent on financial resources, and his had become severely depleted, both (presumably) through his having become a Franciscan, and because of a severe reduction in his family's wealth as a result of their royalist allegiance in the recent troubles in England. One very important way towards the restoration of knowledge was the provision of more and better translations of ancient works, so as to be able to latch more reliably onto an earlier stage in the genealogy of knowledge. He made this point especially strongly with regard to Aristotle, who was one of his greatest heroes. Bacon's early works had typically taken a normal scholastic form of following through a particular Aristotelian text with a series of questions. In his later works he followed his own line of argument, but drew copiously on Aristotle to back up his views, and interestingly he seems often to have drawn not on Aristotle's own text but on a florilegium or florilegia, at least one of which was apparently a source for Johannes de Fonte's Parvi flores or Auctoritates Aristotelis. Aristotle was of course not infallible, but wherever possible Bacon attributed his apparent errors to bad translations.

Bacon's remarks on contemporary translators were scathing and his requirements stringent:

While it is necessary that an interpreter should know excellently the science which he wishes to translate and the two languages from which and into which he translates, only Boethius the first interpreter knew fully the power of languages and only the Lord Robert called Great Head, lately bishop of Lincoln, knew the sciences.

Opus maius, ed. Bridges, 3.82

Bacon himself tried to alleviate the situation by composing a Greek grammar and a fragmentary Hebrew one; his knowledge of Arabic probably remained at best minimal. On the more logical side of grammar he wrote considerably on the theory of linguistic signs, and regarded some logical doctrines, which it is tempting to call merely technical, as having profound philosophical and theological consequences. One such came from the theory of appellation, where Bacon insisted (in accord, as he saw it, with Aristotle) that a name could not univocally signify a being and a non-being, nor something past, present, and future, but only equivocally. (A point of reference here was the question of whether Christ was a man during the three days in the tomb.) Even in 1292 Bacon was fulminating against Richard of Cornwall for promoting the contrary opinion of the crowd back in 1250.

Another important way to restore knowledge was for Bacon that of experimental science (scientia experimentalis). Not surprisingly this phrase has for more than three centuries excited much interest as marking him out as an important, and for the thirteenth century possibly unique, precursor of modern science. Despite much well-reasoned scepticism from modern scholars, this view is not completely unjustified, but it does need to be augmented and modified. Both the Latin terms experientia and experimentum, just like early English ‘experience’ and ‘experiment’, covered a wide range of meanings, from active testing (perhaps in a legalistic sense), through experiences of a quasi-mystical kind, to the experience recognizable in such phrases as ‘long experience’. All these meanings and more can be found in Bacon's discussions of experimental science. In some topics, such as that of the formation of rainbows and of haloes around the sun and moon, his procedures seem very similar to those of modern experimental science, while in others he is reminiscent of Francis Bacon and the compiling of histories (or accounts) of trades, with a view both to increasing knowledge and improving practice; moreover, he often approaches the borderlands of magic.

All this is particularly evident in Bacon's lavish praise of one of his contemporary heroes, Petrus Peregrinus, a man famous for his work on magnetism, but about whom little is known except that he may at times have acted as a military engineer:

He investigated all works of founding metals, and all things that are worked with gold, silver, other metals and all minerals; and he knew all that pertained to warfare and arms and hunting; and he examined all that were for agriculture and the measurement of fields and rural works; also he considered the experiments, divinations and charms of old women and all magicians, and similarly the illusions and devices of all jugglers, so that nothing that should be known would be hidden from him, and he would know how far to reject them as false and magical.

Opus tertium, ed. Brewer, 47

Bacon also moved easily from public to private experience, for he asserted that 'human and philosophical' experience was hardly sufficient for corporeal matters, let alone spiritual ones, and hence internal illuminations, arising from faith and from divine revelations, were necessary, and he even managed to cite from the non-Christian world the view found in the Centiloquium (erroneously ascribed to the astronomer Ptolemy) that 'The way of coming to the knowledge of things is twofold, one by the experience of philosophy, and the other by divine inspiration, which as he says, is much the better' (Opus maius, ed. Bridges, 2.169–70). This draws attention to the theme often found in pre-modern science of revelation as a proper source of scientific knowledge, which can seem less dated if the epithet 'divine' is shed from the term 'inspiration'.


Many of Bacon's schemes remained purely programmatic, but he did make an exception in the case of optics:

If the task is to set forth the individual natural sciences in their proper form, either I shall proceed to this, or others can be incited by my labours. But I do wish to compose a compendious treatise on optics [de perspectiva], because it is more beautiful than the other sciences, and without it nothing can be finely treated.

Opera hactenus inedita, 2.13

Bacon's account of optics was indeed more systematic than that of other special sciences, and this was especially because he was able to draw heavily on the recently translated work of the great Arabic scientist Ibn al-Haytham, who flourished in Egypt in the early eleventh century, and became known in the West as Alhazen. Bacon seems to have been the first Latin writer to have assimilated his work with any thoroughness. A leading idea of Alhazen's treatise was that vision was effected by intromission, that is, by light and colour coming into the eye rather than visual rays being projected out of it. Bacon agreed with Alhazen on intromission, but also insisted that for vision to be completed there must be an action proceeding outwards from the eye. Although this may prima facie seem obscurantist, it was rooted in Bacon's more general doctrines of natural philosophy. Besides his major optical work Alhazen had also written on the theory and practice of constructing parabolic burning mirrors. This drew Bacon's attention especially because of the apparent use of the treatise by Petrus Peregrinus in his pioneering work in making such a mirror in France. Bacon followed his efforts assiduously, and later had several concave mirrors made for his own use.


The optical work of Alhazen, like that of Ptolemy (another of Bacon's heroes), was highly mathematical, a point that greatly appealed to Bacon, and he spoke of geometry as being principally grounded in this science and in astronomy. But this by no means exhausted the range of mathematics' applicability, and Bacon waxed at length about its extreme utility and indeed necessity for a whole gamut of philosophical, theological, and human practical purposes. He himself had a certain, but in the technical sense not a high, level of competence in the subject. He frequently railed at the multiplication of 'useless' conclusions and demonstrations, and most modern mathematicians would look askance at his insistence that even geometrical theorems needed to be certified by the test of experience. Another strategic move that he made in pure mathematics is of some interest. Since at least the time of the Pythagoreans, there had been a tradition of treating arithmetic and geometry as two very distinct sciences: the former dealt with discrete quantity and the latter with continuous quantity, and there were various points (notably incommensurability) that resisted the assimilation of these disciplines. From the Renaissance onwards this divorce was increasingly seen as unsatisfactory, and there were frequent attempts to unite the two subjects under some form of universal mathematics. In antiquity also there had been some attempts at this, and Aristotle provided a few vague hints. Iamblichus, in a work no longer extant, apparently developed the idea further, and Proclus's commentary on Euclid contained a substantial (but still short) discussion of common mathematics. It is therefore of some interest to note that Bacon's first division of mathematics was into things common to the whole of mathematics and those proper to its specialized areas, and that the only completed section of the mathematical volume in his intended grand synthesis was that on the common mathematicals. His discussions are readily reminiscent of Proclus, but the latter's commentary on Euclid is not known to have been available in Latin in the middle ages, and it seems unlikely that Bacon consulted it in Greek. Accordingly the sources of Bacon's discussion remain problematic.

Multiplication of species

Optics not only reinforced Bacon's faith in mathematics: it also suggested a generalization. Bacon's universe was a very active one, and he was extremely interested in how action was transferred from one body to another, especially when they were not in contact. A clear example was the transmission of lighting and heating action from the sun to things below, and Bacon proposed that other forms of action at a distance were of the same kind, whereby substances and qualities radiated species or likenesses of themselves in all directions, which were ‘multiplied’ through the medium in stages, with first one part of the medium being altered, which then altered another adjacent to it, and so on. It is sometimes tempting, but also historiographically hazardous, to compare Bacon's multiplication of species with the nineteenth-century incorporation of optics in a general theory of electromagnetic radiation. It would certainly be fanciful to claim an influence, and Bacon included many actions foreign to most modern conceptions. Prominent among these were astrological and psychic influences. For instance, Bacon had great faith in the power of words: when their utterance was backed up by the right psychological conditions, they were reinforced by corresponding mental species proceeding from the rational soul, and had great power for both good and ill, and this power could be further augmented by species proceeding from the appropriate configuration of the heavens.

Bacon's doctrine was certainly influenced by Grosseteste, but, it would appear, even more more strongly by the De radiis of al-Kindi. This work had the ominous alternative title Theorica artium magicarum, and, despite its short length, Bacon's contemporary Giles of Rome felt able to list eighteen serious errors contained in it. It is therefore not surprising that Bacon did not mention it in the works that he composed for the pope, but he cited it elsewhere, albeit in ambivalent terms. 'The book's author puts forward many excellent things about the multiplication of rays, which are philosophical and true, so that he may the better draw the readers' minds to the poison of falsity that is his principal intent' (De laudibus mathematicae, BL, Royal MS 7 F.vii, fol. 72v). For Bacon, 'false mathematicians', a term that comprehended both magicians and a certain type of astrologer, had two main faults: they held that all things happen of necessity, and they called upon the action of demons. One of the main planks of Bacon's programme was to show that many effects that might vulgarly be accounted magical and dependent upon demons were in fact perfectly legitimate products of art and nature, and his doctrine of the multiplication of species was, by analogy with optics, particularly potent for providing such naturalistic explanations; to this extent al-Kindi's work was a great aid. Less acceptably the Arab philosopher proposed a naturalistic account of the efficacy of prayer, and was a rigorous astrological determinist. This could not be acceptable to Bacon, and determinist interpretations of astrology had for centuries been a principal reason for giving ‘mathematicians’ a bad name, an accusation to which Bacon was very sensitive, and did his utmost to repudiate. Hence al-Kindi was a dangerous friend.

Role of astrology

Nevertheless Bacon was a fervent advocate of the power of astrology, and in this he was strongly backed up by his incorporation of celestial influences into the doctrine of multiplication of species. These influences could be particularly important in the context of Bacon's geographical investigations, for they were potent in explaining how peoples differed from each other in their customs. This gave Bacon visions of technological possibilities, and he was fond of quoting a supposed piece of advice that Aristotle gave to Alexander the Great:

When Alexander found races having very bad customs and wrote to Aristotle about what to do concerning them, that prince of philosophers replied: If you can alter their air, let them live; if not kill them all. Oh what an occult reply this is!—but full of the power of wisdom. For he understood that by a change of the air that contains celestial virtues, men's customs are changed.

Opus maius, ed. Bridges, 1.393

Bacon apparently thought that the required change of air could be brought about by mirrors deflecting the celestial virtues.

More routinely, astrological predictions could allow evasive action if danger seemed to be imminent, and more grandly Bacon following Albumasar (Abu Ma'shar) held that the rise of particular religions could be correlated with planetary conjunctions, although he naturally argued a special status for Christianity. Islam had been the latest moderately worthy candidate on the scene, but very soon there would arise the sect of Antichrist. This would be particularly dangerous, for he would be armed with the sort of technological weapons that Bacon himself wrote about: it was therefore imperative that Christians be likewise provided. Bacon's best-known recommendations were addressed to Pope Clement IV, but he continued similar themes with increased vehemence until the end of his life, which may well have contributed to his supposed confinement. It must, however, be noted that at least in his later years Bacon displayed reservations about the epistemological basis of astrology, and he stressed that not only should a good practitioner of the art be experienced in disciplines ranging from physiognomy through alchemy to agriculture, but that he should himself have been born under the right celestial configuration. The empirical orientation that justifiably recommended him to later ages of natural science is again evident.

Influence and reputation

Roger Bacon's influence was vast but problematic, and at times it is tempting to suspect a conspiracy of silence. For instance, Thomas Bradwardine seems clearly to have used his edition of the Secretum secretorum, and to have been influenced by his views on the growth of knowledge, but in his writings he apparently never mentions his name. John Dumbleton, a younger contemporary of Bradwardine's at Merton College, Oxford, does refer to him in an optical context, but with the peculiarly grudging description as 'one who is called Bakun' (MS Vat. lat. 6750, fol. 194v). On the other hand, in alchemical circles he was sufficiently renowned to have attracted a wealth of pseudepigrapha to his name. Bacon himself did write on alchemy, and prized the science highly. He also showed a delight in the mystification of the subject, as when he told the pope that, although he had written separately four times to him about its secrets, he would still need a viva voce explanation for full understanding. However, Bacon's undoubtedly genuine writings on alchemy are small in volume, and it is hard to feel secure in accepting any of the later ascriptions.

Bacon also acquired a reputation as a magician, but this again has its problems. There seem no grounds for regarding him as the author of such works as a De nigromantia attributed to him, and apart from some stories retailed by a late fourteenth-century Franciscan chronicler, it is not until the sixteenth century that a full account of his supposed doings appears—in an anonymous romance, The Famous Historie of Fryer Bacon, which formed the basis of Robert Greene's well-known play, The Honorable Historie of Frier Bacon, and Frier Bungay. (Bungay incidentally seems to have been a composite figure, formed from an innocent, and possibly dull, thirteenth-century Franciscan and a fifteenth-century friar with a definite reputation for magical practices.) The most famous legend is probably that of the talking brazen head. For England's greater protection Bacon and Bungay learned that they should construct such an object, but it was essential that they actually heard it speak. Enabling it to vocalize involved the advice of a devil and was extremely arduous. It thus turned out that the exhausted friars were asleep when it uttered its few enigmatic words 'Time is—Time was—Time is past': accordingly, as they were deaf to these, it disintegrated in a vast explosion and the project failed. Almost simultaneously with such legends there began the tradition of defending Bacon against charges of magic, and John Dee projected, and perhaps actually wrote, a treatise, 'Mirror of unity, or, Apologia for Friar Roger Bacon the Englishman, in which it is taught that he did nothing by the aid of demons, but was a most great philosopher, and performed naturally and in ways allowable to a Christian man, great things which the unlearned crowd is wont to ascribe to the action of demons' (Dee on Astronomy, 116).

The publishing history of Bacon's works was slow. The only one to appear in print before 1600 was the short but significant Epistola de secretis operibus artis et naturae (Paris, 1542). Some alchemical works (quite probably all spurious) were published in 1603 at Frankfurt under the title Sanioris medicinae … de arte chymiae scripta, and in the same place in 1614 Johann Combach brought out two volumes containing genuine mathematical and optical writings, largely drawn from the Opus maius. Thereafter, for over a century there were only trickles, despite the fact that members of the Royal Society of London in its early days, for whom Bacon had joined his namesake Francis as a hero of experimental science, were anxious to see more of his works in print. In 1733 there appeared in London a large folio volume, edited by Samuel Jebb, which contained most of the Opus maius and the De multiplicatione specierum, but it was only in the nineteenth century and more particularly the early twentieth century that serious editorial and scholarly work on Bacon really began to flourish. He was then often portrayed as a lone beacon of light in an age of darkness, and this understandably provoked a counter-reaction from many medievalists to bring his importance into perspective, and see him as a quite typical, although noisy, product of his own age, who perhaps suffered greatly from ‘sour grapes’ as a failed theologian. More recently emphasis has again been put on his individuality, originality, and influentiality, but now coupled with a determination to locate him much more precisely within the complex and vibrant web of medieval intellectual life.


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  • A. de Libera, ‘Les Summulae dialectices de Roger Bacon [pt 3]’, Archives d'Histoire Doctrinale et Littéraire du Moyen Âge, 54 (1987), 171–278
  • K. M. Fredborg, L. Nielsen, and J. Pinborg, ‘An unedited part of Roger Bacon's Opus maius: De signis’, Traditio, 34 (1978), 75–136
  • F. Alessio, ‘Un secolo di studi su Ruggero Bacone (1848–1957)’, Rivista Critica di Storia della Filosofia, 14 (1959), 81–102
  • J. M. G. Hackett and T. S. Maloney, ‘A Roger Bacon bibliography 1957–85’, New Scholasticism, 61 (1987), 184–207
  • H. Denifle and A. Chatelain, eds., Chartularium universitatis Parisiensis, 4 vols. (Paris, 1889–97)
  • John Dee on astronomy: ‘Propaedeumata aphoristica’ (1558 and 1568), Latin and English, ed. and trans. W. Shumaker (1978)
  • BL, Royal MS 7 F.vii
  • Biblioteca Apostolica Vaticana, Vatican City, MS Vat. lat.
  • Fratris Rogeri Bacon … Opus maius, ed. S. Jebb (1733)



  • drawing, Bodl. Oxf., MS Bodley 211, fol. 5
  • etching, BM, NPG
  • portrait (of Roger Bacon?), repro. in O. Croll, Basilica chymica (1609), title-page
  • portrait (of Roger Bacon?), FM Cam., MS McLean 153, fol. aiiv
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