[Sidenote: Is persecuted and imprisoned.] There is no little significance in the expression of Friar Bacon that the ignorant mind cannot sustain the truth. He was accused of magical practices and of a commerce with Satan, though, during the life of Clement IV., who was his friend, he escaped without public penalties. This pope had written to him a request that he would furnish him an account of his various inventions. In compliance therewith, Bacon sent him the "Opus Majus" and other works, together with several mathematical instruments which he had made with his own hands. But, under the pontificate of Nicolas III., the accusation of magic, astrology, and selling himself to the Devil was again pressed, one point being that he had proposed to construct astronomical tables for the purpose of predicting future events. Apprehending the worst, he tried to defend himself by his work "De Nullitate Magiæ." "Because these things are beyond your comprehension, you call them the works of the Devil; your theologians and canonists abhor them as the productions of magic, regarding them as unworthy of a Christian." But it was in vain. His writings were condemned as containing dangerous and suspected novelties, and he was committed to prison. There he remained for ten years, until, broken in health, he was released from punishment by the intercession of some powerful and commiserating personages. He died at the age of seventy-eight. On his death-bed he uttered the melancholy complaint, "I repent now that I have given myself so much trouble for the love of science." If there be found in his works sentiments that are more agreeable to the age in which he lived than to ours, let us recollect what he says in his third letter to Pope Clement: "It is on account of the ignorance of those with whom I have had to deal that I have not been able to accomplish more."