As a physician, Boyle insisted on facts over theory. He was constantly pleading for physicians to enlarge their experience, to try new medicines, even though these were not based on traditional doctrine. Where observed fact conflicts with theory, the fact cannot be ignored. Credulity of physicians, he indicated, may do the world "more mischief" than any other profession, but nevertheless he condemned those who would try to "circumscribe, or confine the operations of nature, and not so much as allow themselves or others to try, whether it be possible for nature, excited and managed by art, to perform divers things, which they never yet saw done, or work by divers ways, differing from any, which by the common principles, that are taught in the schools, they are able to give a satisfactory account of."[69] Surely, this is not a model of elegant English style, but the message is clear. Boyle was emphasizing the message taught earlier in the century by Francis Bacon, that we must judge the theory by the fact, and not the facts by the theory. It is the same philosophy that Hamlet expounded, that there are more things in heaven and earth than are dreamed of in our philosophy. We see, thus, that Boyle had taken a mighty step toward modern scientific medicine, but he covered only a small part of the total distance. He insisted that we should accept facts, but he did not realize the difficulties attendant on defining a fact and making it credible. He indicated that when strange results are alleged, "these need good proof to make a wary man believe so strange a thing,"[70] but what constitutes proof was a problem which he was not able to wrestle with and, indeed, a problem which he did not clearly perceive. I would emphasize that Boyle was in essence a man of great faith. He had great faith in religion, and was a deeply religious man. He was a great supporter of so-called "natural religion" and tried to reconcile the doctrines of natural philosophy with those of traditional religion. Westfall[71] has considered in detail the religious attitudes of late seventeenth-century writers, Robert Boyle in particular. The "proofs" alleged by the proponents of natural religion have, of course, little cogency. As Westfall points out, they examined nature in order to find what they already believed.