r movement, and finally the
movement takes form; develops leadership, organization; formulates
doctrines and dogmas. Eventually it is accepted, established, legalized.
The movement dies, but the institution remains.

a) _Social contagion._--The ease and the rapidity with which a
cultural trait originating in one cultural group finds its way to other
distant groups is familiar to students of folklore and ethnology. The
manner in which fashions are initiated in some metropolitan community,
and thence make their way, with more or less rapidity, to the provinces
is an illustration of the same phenomenon in a different context.

Fashion plays a much larger role in social life than most of us
imagine. Fashion dominates our manners and dress but it
influences also our sentiments and our modes of thought.
Everything in literature, art or philosophy that was
characteristic of the middle of the nineteenth century, the
"mid-Victorian period," is now quite out of date and no one who
is intelligent now-a-days practices the pruderies, defends the
doctrines, nor shares the enthusiasms of that period.
Philosophy, also, changes with the fashion and Sumner says that
even mathematics and science do the same. Lecky in his history
of Rationalism in Europe describes in great detail how the
belief in witches, so characteristic of the Middle Ages,
gradually disappeared with the period of enlightenment and
progress.[293] But the enlightenment of the eighteenth century
was itself a fashion and is now quite out of date. In the
meantime a new popular and scientific interest is growing up in
obscure mental phenomena which no man with scientific training
would have paid any attention to a few years ago because he did
not believe in such things. It was not good form to do so.

But the changes of fashion are so pervasive, so familiar, and, indeed,
universal phenomena that we do not regard the changes which they bring,
no matter how fantastic, as quite out of the usual and expected order.
Gabriel Tarde, however, regards the "social contagion" represented in
fashion (imitation) as the fundamental social phenomenon.[294]

The term social epidemic, which is, like fashion, a form of social
contagion, has a different origin and a different connotation. J. F. C.
Hecker, whose study of the Dancing Mania of the Middle Ages, published
in 1832, was an incident of h