112. Limitations on the Principle
From the evidences reviewed in this and the last chapter, the conclusion is confirmed which social philosophers had long since reached, that imitation is the normal process by which men live, and that invention is rare, a thing which societies and individuals oppose with more resistance than they are ever aware of, and which probably occurs only as the result of the pressure of special circumstances, although these are as yet little understood. Not only are a hundred instances of diffusion historically traceable for every one of parallelism, but the latter is regularly limited in scope. Something tends to make us see phenomena more parallel than they actually are. They merely spring from the same impulse, they inhere in the properties of objects or nature, they bear resemblance at one point only—and differ at all other points. Yet they tend to impress us, in some mysterious way, as almost identical. The history of civilization has no more produced two like cultures, or two separately developed identical culture traits, than has the evolution of organic life ever duplicated a species by convergently modifying two distinct forms. A whale may look fishlike, he is a mammal. The Hindu and the Maya zero are logically the same; actually they have in common nothing but their abstract value: their shapes, their place in their systems, are different. The most frequent process of culture history therefore is one of tradition or diffusion in time and space, corresponding roughly to hereditary transmission in the field of organic life. Inventions may be thought of as similar to organic mutations, those “spontaneous” variations that from time to time arise and establish themselves. The particular causes of both inventions and mutations remain as good as unknown. Now and then a mutant or an invention heads in the same direction as another previously arisen one. But, since they spring from different antecedents, such convergences never attain identity. They remain on the level of analogous resemblance. Substantial identity, a part for part correspondence, is invariably a sign of common origin, in cultural as well as organic history.
CHAPTER X
THE ARCH AND THE WEEK
[113.] House building and architecture.—[114.] The problem of spanning.—[115.] The column and beam.—[116.] The corbelled arch.—[117.] The true arch.—[118.] Babylonian and Etruscan beginnings.—[119.] The Roman arch and dome.—[120.] Mediæval cathedrals.—[121.] The Arabs: India: modern architecture.—[122.] The week: holy numbers.—[123.] Babylonian discovery of the planets.—[124.] Greek and Egyptian contributions: the astrological combination.—[125.] The names of the days and the Sabbath.—[126.] The week in Christianity, Islam, and eastern Asia.—[127.] Summary of the diffusion.—[128.] Month-thirds and market weeks.—[129.] Leap days as parallels.
In exemplification of the principles discussed in the last two chapters, the next two are given over to a more detailed consideration of several typical ramifying growths whose history happens to be known with satisfactory fullness. These are the arch, the week, and the alphabet.