child's mind develops so that the aid of the picture can be
dispensed with, and the symbolic characters can be used in increasingly
complex ways, in like manner the minds of men living in successive
centuries have evolved. While an evolution of human conceptual processes
in general is not necessarily implied by the evolution of the forms of
written language, the former process is in part demonstrated by the latter
in so far as the change from the writing of pictures to the use of
conventional symbols involves an advance in human ideas of the
interpretation and value of the symbols in question. A man of ancient
times drew a tree to represent his conception of this object; in the
writing of English we now use four letters to stand for the same object,
and none of these symbols is in any way a replica of the tree. It is
certainly obvious that some change in the mental association of symbol and
object has been brought about, and to this extent there has been mental
evolution.

* * * * *

Passing now to other departments of human culture, we must deal in the
next place with the basic "arts of life"; that is, the modes of conducting
the necessary activities of every day. All men of all times, be they
civilized or savage, are impelled like the brutes by their biological
nature to seek food and to repel their foes. The rough stone club and ax
were fashioned by the first savage men, when diminishing physical prowess
placed them at a disadvantage in the competition with stronger animals.
Smoother and more efficient weapons were made by the hordes of their more
advanced descendants, some of whom remained in the mental and cultural
condition of the stone age like the Fuegian, until the white travelers of
recent centuries brought them newer ideas and implements. In Europe and
elsewhere the period of stone gave place to the bronze and iron ages, and
throughout the changing years human inventiveness improved the missile and
weapon to become the bow and arrow of medieval civilization and recent
African savagery. The artillery and shells of modern warfare are their
still more highly evolved descendants.

So it is with the dwellings of men, and the significance of the changes
displayed by such things. The cave was a natural shelter for primitive man
as well as for the wolf, and it is still used by men to-day. Where it did
not exist, a leafy screen of branches served in its stead; even now there
are human