It may, indeed, be objected that in practical life no perfectly satisfactory experiments exist as to the respective mental qualities of men and women, since men and women are never found working under conditions that are exactly the same for both sexes. If, however, we turn to the psychological laboratory, where it is possible to carry on experiments under precisely identical conditions, the results are still the same. There are nearly always differences between men and women, but these differences are complex and manifold; they do not always agree; they never show any general piling up of the advantages on the side of one sex or of the other. In reaction-time, in delicacy of sensory perception, in accuracy of estimation and precision of movement, there are nearly always sexual differences, a few that are fairly constant, many that differ at different ages, in various countries, or even in different groups of individuals. We cannot usually explain these differences or attach any precise significance to them, any more than we can say why it is that (at all events in America) blue is most often the favourite colour of men and red of women. We may be sure that these things have a meaning, and often a really fundamental significance, but at present, for the most part, they remain mysterious to us. When we attempt to survey and sum up all the variegated facts which science and practical life are slowly accumulating with reference to the mental differences between men and women[4] we reach two main conclusions. On the one hand there is a fundamental equality of the sexes. It would certainly appear that women vary within a narrower range than men--that is to say, that the two extremes of genius and of idiocy are both more likely to show themselves in men. This implies that the pioneers in progress are most likely to be men. That, indeed, may be said to be a biological fact. "In all that concerns the evolution of ornamental characters the male leads; in him we see the trend which evolution is taking; the female and young afford us the measure of their advance along the new line which has to be taken."[5] In the human sphere of the arts and sciences, similarly, men, not women, take the lead. That men were the first decorative artists, rather than women, is indicated by the fact that the natural objects designed by early pre-historic artists were mainly women and wild beasts, that is to say, they were the work of masculine hunters, executed in idle intervals of the chase. But within the range in which nearly all of us move, there are always many men who in mental respects can do what most women can do, many women who can do what most men can do. We are not justified in excluding a whole sex absolutely from any field. In so doing we should certainly be depriving the world of some portion of its executive ability. The sexes may always safely be left to find their own levels.