The scientific materialists obstinately refused to acknowledge capricious or creative forces directing natural processes from outside nature. Büchner, for example, had an unwavering confidence in what he called the unity and regularity of natural events. No fact that would ever come to light, no advance of science, he said, would ever impair this conviction, now shared by every impartial student of nature.¹ One of his last words revealed that his major motivation had not been so much materialism, not so much monism as it had been Feuerbachian naturalism.