Religious conversion and its psychology have furnished the world's library with many volumes. Perfectly understood in the ages of faith, the subject is for modern thinkers susceptible of realistic explanation. Only we pave the way now by a psychological course instead of the ancient doctrine of Grace Abounding. Nor do we confound the irresistible desire of certain temperaments to spill their innermost thoughts, with what is called conversion. There was Rousseau, who confessed things that the world would be better without having heard. He was not converted. Tolstoy, believing that primitive Christianity is almost lost to his fellow beings, preaches what he thinks is the real faith. Yet he was converted. He had been, he said, a terrible transgressor. The grace of God gave sight to his sin-saturated eyeballs. Is there the slightest analogy between his case and that of Cardinal Newman? John Henry Newman had led a spotless life before he left the Anglican fold. Nevertheless he was a convert. And Saint Augustine, the pattern of all self-confessors, the classic case, may be compared to John Bunyan or to Saint Paul! Professor William James, who with his admirable impartiality has scrutinized the psychological topsy-turvy we name conversion, has not missed the commonplace fact that every man as to details varies, but at base the psychical machinery is controlled by the same motor impulses. _A chacun son infini._ Some natures reveal a mania for confession. Dostoïevsky's men and women continually tell what they have thought, what crimes they have committed. It was an epileptic obsession with this unhappy Russian writer. Paul Verlaine sang blithely of his ghastly life, and Baudelaire did not spare himself. So it would seem that the inability of certain natures to keep their most precious secrets is also the keynote of religious confessions. But let us not muddle this with the sincerity or insincerity of the change. Leslie Stephen has said that it did not matter much whether Pascal was sincere, and instanced the Pascal wager (_le pari de Pascal_) as evidence of the great thinker's casuistry. It is better to believe and be on the safe side than be damned if you do not believe; for if there is no hereafter your believing that there is will not matter one way or the other. This is the substance of Pascal's wager, and it must be admitted that the ardent upholder of Jansenism and the opponent of the Jesuits proved himself an excellent pupil of the latter when he framed his famous proposition.