It is recorded that Diderot's own last words in serious conversation were: "The beginning of philosophy is incredulity"; and it may be inferred from his writings that his first impulses to searching thought came from his study of Montaigne, who must always have been for him one of the most congenial of spirits. [1102] At an early stage of his independent mental life we find him turning to the literature which in that age yielded to such a mind as his the largest measure both of nutriment and stimulus--the English. In 1745 he translated Shaftesbury's Inquiry concerning Virtue and Merit; and he must have read with prompt appreciation the other English freethinkers then famous. Ere long, however, he had risen above the deistical plane of thought, and grappled with the fundamental issues which the deists took for granted, partly because of an innate bent to psychological analysis, partly because he was more interested in scientific problems than in scholarly research. The Pensées philosophiques, published in 1746, really deserve their name; and though they exhibit him as still a satisfied deist, and an opponent of the constructive atheism then beginning to suggest itself, they contain abstract reasonings sufficiently disturbing to the deistic position. [1103] The Promenade du Sceptique (written about 1747, published posthumously) goes further, and presents tentatively the reply to the design argument which was adopted by Hume. In its brilliant pages may be found a conspectus of the intellectual life of the day, on the side of the religious problem. Every type of thinker is there tersely characterized--the orthodox, the deist, the atheist, the sheer skeptic, the scoffer, the pantheist, the solipsist, and the freethinking libertine, the last figuring as no small nuisance to the serious unbeliever. So drastic is the criticism of orthodoxy that the book was unprintable in its day; [1104] and it was little known even in manuscript. But ere long there appeared the Letter on the Blind, for the use of those who see (1749), in which a logical rebuttal alike of the ethical and the cosmological assumptions of theism, developed from hints in the Pensées, is put in the mouth of the blind English mathematician, Sanderson. It is not surprising that whereas the Pensées had been, with some other books, ordered by the Paris Parlement to be burnt by the common hangman, the Lettre sur les Aveugles led to his arrest and an imprisonment of six months [1105] in the Château de Vincennes. Both books had of course been published without licence; [1106] but the second book was more than a defiance of the censorship: it was a challenge alike to the philosophy and the faith of Christendom; and as such could not have missed denunciation. [1107]