DECEMBER 24, 1897. ] - 
nervous disposition than the other; in 
which case every one would speak of the 
former as naturally (7. e., innately, instine- 
tively ) more timid than his brother, though, 
in fact, his excess of timidity would be ac- 
quired. 
In practice, owing to the necessity of the 
case, we act as if we realized that man’s 
mind, his character, his disposition, is al- 
most entirely acquired; and, therefore, 
every parent carefully trains his child for a 
prolonged period, striving by precept and 
example to inculcate fit mental traits, that 
is, fit knowledge and ways of thinking and 
acting. Even the savage mother does this, 
and civilized nations have vast state estab- 
lishments for educating their youth. More- 
over, we realize that a child reared by the 
brave or the cowardly, the active or sloth- 
ful, the moral or the immoral, the patriotic 
or the non-patriotic, the devout or the scep- 
tical, and so forth, will exhibit the traits of 
his educators, even if they be not his pro- 
genitors. In fact, we realize, as regards man 
(though this is not true as regards such 
animals as the dragon-fly, in which, as we 
have seen, the mentally acquired is practi- 
cally non-existent), that the mind of one 
generation imprints itself on the mind of 
the next, not racially, but educationally ; 
but, in thinking of this or that adult man, 
or this or that race of men, we are apt to 
consider their mental peculiarities as innate 
and acquired. Hspecially is this done by 
men of learning, historians, anthropologists, 
psychologists, philosophers and the like. 
It is not realized by them that man’s real 
mental evolution has lain in the evolution of his 
power of acquiring mental traits, and that not 
in a single other inborn peculiarity does he 
mentally transcend lower animals, and, 
therefore, that one adult individual or race 
must differ from another individual or race 
wholly in the traits that are acquired, and 
in the power of acquiring them. For example, 
no man or race is born with greater mu- 
SCIENCE. 
943 
sical, artistic or mathematical powers than 
any other man or race, but merely with 
greater powers of acquiring them ; for, in 
the absence of appropriate stimulation (7%. e., 
experience, education), they do not develop 
even in the most ‘gifted.’ It seems proba- 
ble, moreover, that powers of acquiring 
these and other particular faculties have not 
been separately and especially evolved by 
Natural Selection, but, on the contrary, that 
they are but particular manifestations of 
the general power of acquiring mental 
traits, which is what has been evolved by 
Natural Selection.* Thus there appears to 
be no more reason for supposing that the 
mathematical faculty has been especially 
evolved than for supposing that the faculty 
for understanding the uses of machinery 
has been evolved; both the one and the 
other must have been equally useless to the 
primitive savage. 
In lower animals the amount of mental 
receptivity is closely associated with the 
size of the brain, the larger brain being the 
concomitant of greater receptivity, and, 
as a consequence, of lessened instinct. As- 
sociated with this truth is the fact that 
modern representatives of ancient animals 
(e. g., ungulates) have much larger brains 
than their ancestors, denoting the evolution 
in them of the supremely important faculty 
of acquiring mental characters. Now, 
since so little that is mental is inborn in 
man while so much is acquired, we must 
conclude that differences in the sizes and 
shapes of the brains of different races imply 
not inborn mental differences, but differ- 
ences in the power of acquiring mental 
characters, and, therefore, for example, 
that the native Australian, with his small 
* Of course, I do not mean by this that the man 
who is capable, for instance, of high musical attain- 
ments, is also necessarily capable of high mathemat- 
ical attainments. We know that this is not so. 
Nevertheless, even as regards these faculties much 
must depend on the ‘bent’ given to the individual’s 
mind by circumstances occurring early in life. 
