The tendency of mankind to split up everything into three is hard to explain rationally. It is either false and a piece of superstition; or it is true and a part of religion. In either case it cannot be adequately explained on ordinary human judgment or average human experience. Three is really a very uncommon number in nature. The dual principle runs through nature as a whole; it is almost as if our earth and heaven had been made by the Heavenly Twins. There is no beast with three horns, no bird with three wings; no fish with three fins and no more. No monster has three eyes, except in fairy tales; no cat has three tails, except in logic. Sages have proved the world to be flat and round and oblate and oval; but none (as far as I know) have yet proved it to be triangular. Indeed, the triangle is one of the rarest shapes, not merely in the primal pattern of the cosmos, but even in the multifarious details of man’s civilization. There are three-cornered hats, certainly, and three-cornered tarts; but even taken together they scarcely provide the whole equipment of civilization. Three-cornered tarts might be monotonous as a diet; as three-cornered hats would certainly be inadequate as a costume. The tripod was certainly important in pagan antiquity; but I cannot help thinking that its modern representative, the three-legged stool, has rather come down in the world. Evolution and the Struggle for Life (if I may mention such holy things in so light a connection) seem to have gone rather against the tripod; and even the three-legged stool is not so common as it was. Victory has gone to the quadrupeds of furniture: to the huge, ruthless sofas, the rampant and swaggering armchairs. It seems clear, therefore, that there is nothing in common human necessities, just as there is nothing in the structure and system of the physical world, to impregnate man with his curious taste for the number three. Yet he shows it in everything from the Three Brothers in the fairy-tale to the Three Estates of the realm; in everything from the Three Dimensions to the Three Bears. If the thing has a reason, it must be a reason beyond reason. It must be mystical; it may be theological.
— The Illustrated London News, 10 December 1910.