m the staple currency of his beliefs and his
conversation. Reason plays a surprisingly small part in this process,
for most human beings acquire from their fellows the traditions of their
society which relieves them of the necessity of undue thought. The very
words in which the accumulated traditions of his community are conveyed
to each individual are themselves charged with the complex symbolism
that has slowly developed during the ages, and tinges the whole of his
thoughts with their subtle and, to most men, vaguely appreciated shades
of meaning.[9] During this process of acquiring the fruits of his
community's beliefs and experiences every individual accepts without
question a vast number of apparently simple customs and ideas. He is apt
to regard them as obvious, and to assume that reason led him to accept
them or be guided by them, although when the specific question is put to
him he is unable to give their real history.

Before leaving these general considerations[10] I want to emphasize
certain elementary facts of psychology which are often ignored by those
who investigate the early history of civilization.

First, the multitude and the complexity of the circumstances that are
necessary to lead men to make even the simplest invention render the
concatenation of all of these conditions wholly independently on a
second occasion in the highest degree improbable. Until very definite
and conclusive evidence is forthcoming in any individual case it can
safely be assumed that no ethnologically significant innovation in
customs or beliefs has ever been made twice.

Those critics who have recently attempted to dispose of this claim by
referring to the work of the Patent Office thereby display a singular
lack of appreciation of the real point at issue. For the ethnological
problem is concerned with different populations who are assumed _not_ to
share any common heritage of acquired knowledge, nor to have had any
contact, direct or indirect, the one with the other. But the inventors
who resort to the Patent Office are all of them persons supplied with
information from the storehouse of our common civilization; and the
inventions which they seek to protect from imitation by others are
merely developments of the heritage of all civilized peoples. Even when
similar inventions are made apparently independently under such
circumstances, in most cases they can be explained by the fact that two
investigators have followed up a