ch belief, institution, custom, and
arrangement was modified; and how the _consensus_ of preceding
structures and functions was developed into the _consensus_ of
succeeding ones. Such alone is the kind of information respecting past
times which can be of service to the citizen for the regulation of his
conduct. The only history that is of practical value is what may be
called Descriptive Sociology. And the highest office which the historian
can discharge, is that of so narrating the lives of nations, as to
furnish materials for a Comparative Sociology; and for the subsequent
determination of the ultimate laws to which social phenomena conform.

But now mark, that even supposing an adequate stock of this truly
valuable historical knowledge has been acquired, it is of comparatively
little use without the key. And the key is to be found only in Science.
In the absence of the generalisations of biology and psychology,
rational interpretation of social phenomena is impossible. Only in
proportion as men draw certain rude, empirical inferences respecting
human nature, are they enabled to understand even the simplest facts of
social life: as, for instance, the relation between supply and demand.
And if the most elementary truths of sociology cannot be reached until
some knowledge is obtained of how men generally think, feel, and act
under given circumstances; then it is manifest that there can be nothing
like a wide comprehension of sociology, unless through a competent
acquaintance with man in all his faculties, bodily, and mental. Consider
the matter in the abstract, and this conclusion is self-evident.
Thus:--Society is made up of individuals; all that is done in society is
done by the combined actions of individuals; and therefore, in
individual actions only can be found the solutions of social phenomena.
But the actions of individuals depend on the laws of their natures; and
their actions cannot be understood until these laws are understood.
These laws, however, when reduced to their simplest expressions, prove
to be corollaries from the laws of body and mind in general. Hence it
follows, that biology and psychology are indispensable as interpreters
of sociology. Or, to state the conclusions still more simply:--all
social phenomena are phenomena of life--are the most complex
manifestations of life--must conform to the laws of life--and can be
understood only when the laws of life are understood. Thus, then, for
the regulat