long anywhere. It was succeeded by that metal which, beyond all
others, has been of signal utility to man--iron. We live in the iron
age, and it is from iron in some of its forms and products that all
our best weapons and materials for implements, etc., are derived. We
have, therefore, the ages of stone, of bronze and of iron. These are
the measures, from an artistic source, of the advancement of human
culture; and they certainly bear a distinct relation to all man's
other conditions at the time. A tribe which had never progressed
beyond the stone age--which had no better material for its weapons and
implements than stone--could never proceed beyond a very limited point
of civilization. Bronze or any metal which can be moulded, hammered
and sharpened of course gives a nation vast superiority over one which
uses stone only; and the value of iron and steel for the same purposes
I need not dwell upon.

To be sure, we have here several measures; and it would seem more
desirable, if we could, to obtain one single measure--one single
material or object of which we could say that the tribe that uses or
does not use that to an equal degree is certainly lower or, in the
other respects, higher than another; but I believe that there has been
no single material which has been suggested as of sufficient use and
value in this direction to serve as a criterion; but, yes! I remember
there was one and, on the whole, not a bad one. It was suggested by
Baron Liebig, the celebrated chemist, who said: "If you wish a single
material by which to judge of the amount of culture that any nation,
or, for that matter, any individual, possesses, compared to another
one, find out how much soap they use. Nothing," he said, "more than
personal cleanliness and general cleanliness differentiates the
cultured man from the savage;" and as for that purpose he probably had
in view a soap, he recognized that as the one criterion. It is not