His contempt for the kind of work by which honour was there eained is unmeasured, and for his own part, with such aid as was afforded by the increasing knowledge of the Arab writers, he devoted himself to acquiring a knowledge of languages, and to experimental researches, partly in alchemy, partly in optics.
About the year 1250 Bacon seems to have returned to England, and though no details are known of the next definable period of his life extending up to 1257, the tradition may; be accepted that he spent the time mainly; at Oxford. The legendary connection between his name and the university of Oxford doubtless dates from this residence. That he had left Oxford in 1257 is attested by Bacon himself (Op. Ined. p, 7), but of the surrounding circumstances extremely little is known. The immediate occasion was the suspicion of his superiors in the Franciscan order, who, perhaps even before the date given, had put him under surveillance, and in 1257 sent him to Paris. At what time or for what reasons he had joined the Franciscan order, there are no means of determining. As he refers pointedly to the fact that he had not written anything 'in alio statu,' we may conjecture that he did not enter at a very early age. It was under the generalship of John of Fidanza, better known as Bonaventura, that Bacon was placed under restraint, and for ten years he was kept in close confinement in Paris. During that time he was denied all opportunity of writing; books and instruments were taken from him, and the most jealous care was taken that he should have no communication with the outer world.
Partial relief came from an unexpected quarter. In 1265 Guy de Foulques, who had in the previous year acted as papal legate in England, was raised to the papal chair as Clement IV. During his residence in England he had made various attempts to communicate with Bacon, and had solicited from him a general treatise on the sciences which rumour spoke of as completed. Bacon, who had no such general treatise ready, had been unable to reply to the friendly request, but, after the elevation of Guy de Foulques, was successful in privately laying before him a statement of the circumstances which had prevented his earlier reply. In answer the pope sent a letter enjoining Bacon to forward to him secretly and privately any writing he could prepare, notwithstanding all injunctions to the contrary of his superiors (the letter is given in Brewer's Op. Ined. p. 1).
The opening chapters of the writing called 'Opus Tertium' give a very vivid picture of Bacon's circumstances when he received this mandate, of the joy with which he hailed the opportunity afforded to him, of the manifold difficulties in the way of completing the work on which he forthwith entered, and of the plan he adopted for laying the substance of his reflections before his friendly auditor. Deeply impressed with a sense of the unity of the sciences, he thought it well first to treat in a general way of the various parts of human knowledge, giving a conspectus or compendious view of the whole before approaching the detailed treatment of the parts. This general view forms the 'Opus Majus,' and apparently the composition and copying must have been accomplished within a wonderfully brief space of time. For within almost two years from the time of receiving Clement's mandate, Bacon, in the 'Opus Tertium,' refers to the 'Opus Majus' as already sent off, and also to a subsequent writing, the 'Opus Secundum,' or 'Opus Minus,' in which an abridgment of the larger work had been given, with a special treatment of some essential subjects omitted either by design or by pressure of circumstances. Still desirous of conveying his thought in such a way as to win the ear of his powerful patron. Bacon forthwith began a new treatment of the whole, and in the seventy-five chapters printed under the title of the 'Opus Tertium' we have at least a portion of his new treatment. The 'Opus Tertium ' in its printed form contains an expanded summary of the main portions of the 'Opus Majus;' but as it makes frequent reference to other writings which were intended to be laid before Clement, it is probable that we have in it only a fragment of a larger work. Evidently during the composition of the 'Opus Tertium' Bacon was relieved from much of the restraint under which he had been suffering, and in 1268 he was again in England. Whether the other writings referred to in the extant chapters of the 'Opus Tertium' were composed in time to be sent to Clement (who died in November 1268) we cannot determine. In all probability they were not, and this circumstance may to some extent account for certain difficulties presented by the manuscripts to be afterwards referred to.
That Clement exerted himself on behalf of Bacon is a mere conjecture; it is certain that after 1267 he was in comparative freedom, and we may suppose devoted himself to working out, in special writings, the particular sciences forming in his conception the body of knowledge. There remain fragments of a work, part of which undoubtedly was written in 1271 or 1272 (Brewer, Op. Ined. pref p. 55), a compendium of philosophy, the projected
