Of all the possible ways of treating the brain for the purpose of testing its intelligence, that of weighing is the least satisfactory, and has been most indefatigably practiced.  A better method, that of counting the nerve cells, has been lately introduced, but to treat a single brain in this way is a work of years, and no series of results exists.  In the meantime Miss Thompson, in co-operation with Professor Angell, has completed a study of the mental traits of men and women on what is perhaps the best available principle—­that of a series of laboratory tests which eliminate or take into consideration differences due to the characteristic habits of the two sexes.  Her findings are probably the most important contribution in this field, and her general conclusion on differences of sex will, I think, hold also for differences of race: 

The point to be emphasized as the outcome of this study is that, according to our present light, the psychological differences of sex seem to be largely due, not to difference of average capacity, nor to difference in type of mental activity, but to differences in the social influences brought to bear on the developing individual from early infancy to adult years.  The question of the future development of the intellectual life of women is one of social necessities and ideals rather than of the inborn psychological characteristics of sex.[258]

There is certainly great difference in the mental ability of individuals, and there are probably less marked differences in the average ability of different races; but difference in natural ability is, in the main, a characteristic of the individual, not of race or of sex.  It is probable that brain efficiency (speaking from the biological standpoint) has been, on the average, approximately the same in all races and in both sexes since nature first made up a good working-model, and that differences in intellectual expression are mainly social rather than biological, dependent on the fact that different stages of culture present different experiences to the mind, and adventitious circumstances direct the attention to different fields of interest.

II

In approaching the question of the parity or disparity of the mental ability of the white and the lower races, we bring to it a fixed and instinctive prejudice.  No race views another race with that generosity with which it views itself.  It may even be said that the existence of a social group depends on its taking an exaggerated view of its own importance; and in a state of nature, at least, the same is true of the individual.  If self-preservation is the first law of nature, there must be on the mental side an acute consciousness of self, and a habit of regarding the self as of more importance than the world at large.  The value of this standpoint lies in the fact that, while a wholesome fear of the enemy is important,