This, however, suggests another and very difficult series of problems. Mr. Kidd is arguing against intellectual superiority. He, of course, does not argue that the general superiority of a race leads to its disappearance; but that a one-sided superiority--an improvement of one set of faculties at the expense of others--may have that result. This at once suggests a whole series of psychological problems. The intellect and the emotional nature are not two separate organs, each capable of independent development. Every mental process involves both, and neither faculty can be developed without reference to the other. Mr. Kidd accepts the conclusion that certain primitive races were as clever as ourselves, because their brains were as large. If the argument be sound, it proves equally that their emotional nature was as well developed as ours; for no one can doubt that the brain is the physical condition of feeling as well as of thought. Even the most abstract thought, as he elsewhere notices, implies certain moral qualities. Newton remarked that he was superior to other men, not because his intellect was clearer, but because he attended more persistently to his problems. The statement, I think, involves a fallacy. Newton himself, no doubt, did better the longer he kept a problem before him. He inferred, unjustifiably, that of two different men, the one who could keep up his attention longest would be the best. That does not follow. The difference may indeed be moral as well as intellectual; and it is quite true that a power of sustained attention is of the highest importance in mathematics, and that that power supposes a moral quality; but, conversely, the power of attention probably implies also the power of clear intellectual vision. A muddle-headed man would find attention useless. This is, of course, still clearer in the case where the mind is exercised upon questions of human interest. The statesman and the dramatist both depend upon their power of sympathy and the strength of their emotions, as much as upon their logical capacity. To feel for others I must imagine their position: if I imagine it, I can hardly avoid feeling for them. "Altruism" is the product, in other words, of a process both intellectual and moral.