Throughout this chapter, I am glad to acknowledge a heavy debt to the works of Dr Charles Singer, whose volume on Religion and Science in Benn's Sixpenny Library should be read by all who are interested in this subject; they will then probably wish to pass on to his larger works.

The decay of science cannot be directly credited to the rise of Christianity; Greek and Roman science had been in full decay before Constantine's recognition of this as the favoured religion of the Empire. In those days, at any rate, Christianity came as a healthy protest against the pessimistic materialism which coloured so much of ancient thought; it objected not to actual observation and experiment (for those were no longer living forces in the Empire), but to the philosophical generalizations of paganism. For a living science two factors are essential: observation and synthesis. Observation must be patient and open-minded; synthesis must be bold and imaginative; each, sincerely used, stimulates, corrects, and supplements the other. This combination, in the Middle Ages, was nearly always imperfect. There was so little penetrating first-hand observation, in proportion to the collection and preservation of past traditions, that Dr Singer can write, without more injustice than is inherent in a single brief and epigrammatic sentence, “Medieval medicine may be summed up as a corrupted version of Galenism.” In other words, medical science stood still—or even, to some extent, went backwards, from a.d. 200 to nearly 1500.