This, after all, is the field in which medieval science can best be studied; for here we have something in which all men are interested, great and small. Why was medieval progress so slow in a matter so vital to every rank of society? It is fairly comprehensible that clerical conservatism should have cared little for Bacon's ideal of a scientifically accurate Bible or accurate translations from the Greek Fathers; and, again, that nobody should have paid attention to his hint of possible aeronautics; or, still further, that his similar surmise of an American Continent should have slumbered until it was picked up by Cardinal Peter d'Ailly in the fifteenth century, and treated more seriously by Columbus a couple of generations later. We are not so very much surprised, again, that Europe should not have taken to printing until more than a century after Marco Polo's description of China might have shown the way. But it is far more strange that, in medicine, Dr Singer can pass on from the death of Galen (a.d. 199) to write, “the Dark Ages [for medicine] have begun. Anatomy in the pagan world descends into darkness more abruptly, but not more surely, than philosophy.” Here again we must note what the date proves, that it is not merely a question of Christian influence; decay had already set in before Constantine the Great. But why, when the world settled down again, was there not a more real advance in medicine?