rs are elementary and restricted, but these same powers change and
intensify so as to render the older mind quite capable of grasping the
highest of human conceptions and ideas. In my judgment the unbroken
transformation of a child's mind that exhibits only instinct and
intelligence into an adult's mind with its power of reasoning, is far more
conclusive as proof of mental evolution than the inference drawn from the
comparisons we have made above of the adult psychological phenomena of
man, ape, cat, and fish. It is surely natural for such mental
transformations to take place, for they do take place in the vast majority
of human beings; when they do not, in cases where the brain fails to
mature, we speak of unnatural or diseased minds.

The third division of our evidence relating to mental evolution
constitutes what we have called the palaeontology of mind. By this term we
mean the study of human minds of the past as we may know them through the
many varied relics and documents which indicate their characters. It is
only too obvious to every one that human knowledge has advanced in the
course of time and that every department of human thought and mental
activity has participated in this progress. No one would have the temerity
to assert that we know nothing more than our ancestors of 5000 or even
1000 years ago. Our common-sense teaches us even before the man of science
produces the full body of evidence at his disposal that human faculties
have evolved. With regard to reasoning powers, which form one of the four
distinguishing characteristics of the human species as contrasted with
other animals, the case has already been reviewed, and we now turn to
speech and language and other departments of human mentality. When we
compare the attainments of present day men with the abilities and ideas of
their ancestors we will do for mental phenomena precisely what was done
when we compared the skeletons of modern animals with those of creatures
belonging to bygone geological ages; in this reason is found the
justification for the phrase employed in the present connection.

Written history furnishes a wealth of material for interpreting the mental
conditions of ancient peoples, but beside documentary evidence the
anthropologist learns to use inscriptions of prehistoric times, the
primitive graphic representations on tombs and monuments, and even the
characteristics of crude implements like axes and arrow-heads. The layman
finds i