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Dismissing abstract difference of quality, a thing difficult to verify, the efficiency of an organ is known to depend not solely on its size but on its activity: and of this we have an approximate measure in the energy with which the blood circulates through it, both the stimulus and the reparative force being mainly dependent on the circulation. It would not be surprising—it is indeed an hypothesis which accords well with the differences actually observed between the mental operations of the two sexes—if men on the average should have the advantage in the size of the brain, and women in activity of cerebral circulation. The results which conjecture, founded on analogy, would lead us to expect from this difference of organization, would correspond to some of those which we most commonly see. In the first place, the mental operations of men might be expected to be slower. They would neither be so prompt as women in thinking, nor so quick to feel. Large bodies take more time to get into full action. On the other hand, when once got thoroughly into play, men's brain would bear more work. It would be more persistent in the line first taken; it would have more difficulty in changing from one mode of action to another, but, in the one thing it was doing, it could go on longer without loss of power or sense of fatigue. And do we not find that
