Physical science has everything in the world to do with fancy, though not perhaps much in the highest sense to do with imagination. Imagination as we have it in great poetry is concerned with the things that fall naturally into an harmonious picture; but fancy is concerned with things which conceal an intellectual affinity under a total pictorial difference. Imagination celebrates the stars and clouds together, but fancy and physical science alike see that a squib or a pipe-light, or perhaps even a humming-top, are more akin to the stars than a cloud is. The whole fascination of science lies in this disguised fraternity. Nature in this aspect seems made of secret societies in the darkest and most misleading costumes. No elf-land of the human fancy can offer a kingdom so preposterous as that in which a whale is nearer to a bat than a whale to a shark, or a bat to a bird. This general consciousness that the most perfect similarities exist in the most diverse examples is a thing that much have haunted the minds of hundreds of good-working physicians [.]

-G.K.C. as M.C. (1929)