ons of his dealings in the black arts and
with some doubts of his orthodoxy. About 1257, Bonaventura, general of the
order, interdicted his lectures at Oxford, and commanded him to place
himself under the superintendence of the body at Paris. Here for ten years
he remained under supervision, suffering great privations and strictly
prohibited from writing anything for publication. But his fame had reached
the ears of the papal legate in England, Guy de Foulques, who in 1265
became pope as Clement IV. In the following year he wrote to Bacon,
ordering him notwithstanding any injunctions from his superiors, to write
out and send to him a treatise on the sciences which he had already asked
of him when papal legate. Bacon, whose previous writings had been mostly
scattered tracts, _capitula quaedam_, took fresh courage from this command
of the pope. He set at naught the jealousy of his superiors and brother
friars, and despite the want of funds, instruments, materials for copying
and skilled copyists, completed in about eighteen months three large
treatises, the _Opus Majus_, _Opus Minus_ and _Opus Tertium_, which, with
some other tracts, were despatched to the pope. We do not know what opinion
Clement formed of them, but before his death he seems to have bestirred
himself on Bacon's behalf, for in 1268 the latter was permitted to return
to Oxford. Here he continued his labours in experimental science and also
in the composition of complete treatises. The works sent to Clement he
regarded as preliminaries, laying down principles which were afterwards to
be applied to the sciences. The first part of an encyclopaedic work
probably remains to us in the _Compendium Studii Philosophiae_ (1271). In
this work Bacon makes a vehement attack upon the ignorance and vices of the
clergy and monks, and generally upon the insufficiency of the existing
studies. In 1278 his books were condemned by Jerome de Ascoli, general of
the Franciscans, afterwards Pope Nicholas IV., and he himself was thrown
into prison for fourteen years. During this time, it is said, he wrote the
small tract _De Retardandis Senectutis Accidentibus_, but this is merely a
tradition. In 1292, as appears from what is probably his latest
composition, the _Compendium Studii Theologiae_, he was again at liberty.
The exact time of his death cannot be determined; 1294 is probably as
accurate a date as can be fixed upon.

_Works and Editions_.--Leland said that it is easier to col