History, however, is very uneven; and it is necessary to read texts and sources that for form are not worth reading. And the same with philosophy. Mathematics and science, pure or physical, could not, of course, be covered with the same speed. Yet, with time available, all could be mastered. There is no concept ever expressed by any human mind that cannot be comprehended by any other normal human mind, if time is available and it is taken in the proper order and context and with the proper preparatory work. And often, and now more often, Vincent felt that he was touching the fingers of the secret; and always, when he came near it, it had a little bit the smell of the pit. For he had pegged out all the main points of the history of man; or rather most of the tenable, or at least possible, theories of the history of man. It was hard to hold the main line of it, that double road of rationality and revelation that should lead always to a fuller and fuller development (not the fetish of progress, that toy word used only by toy people), to an unfolding and growth and perfectibility. But the main line was often obscure and all but obliterated, and traced through fog and miasma. He had accepted the Fall of Man and the Redemption as the cardinal points of history. But he understood now that neither happened only once, that both were of constant occurrence; that there was a hand reaching up from that old pit with its shadow over man. And he had come to picture that hand in his dreams (for his dreams were especially vivid when in the state) as a six-digited monster reaching out. He began to realize that the thing he was caught in was dangerous and deadly. Very dangerous. Very deadly. One of the weird books that he often returned to and which continually puzzled him was the Relationship of Extradigitalism to Genius, written by the man whose face he had never seen, in one of his manifestations. It promised more than it delivered, and it intimated more than it said. Its theory was tedious and tenuous, bolstered with undigested mountains of doubtful data. It left him unconvinced that persons of genius (even if it could be agreed who or what they were) had often the oddity of extra fingers and toes, or the vestiges of them. And it puzzled him what possible difference it could make.