Thomas Huxley, to take a name known to all, was a man in whom there was much fruitful hostility. He did not seek controversy, but when the enemies of truth offered battle he felt no inclination to refuse; and he avowed—perhaps with a certain zest in contravening conventional teaching—that he loved his friends and hated his enemies.[69] His hatred was of a noble sort, and the reader of his Life and Letters can hardly doubt that he was a good as well as a great man, or that his pugnacity helped him to be such. Indeed I do not think that science or letters could do without the spirit of opposition, although much energy is dissipated and much thought clouded by it. Even men like Darwin or Emerson, who seem to wish nothing more than to live at peace with everyone, may be observed to develop their views with unusual fulness and vigor where they are most in opposition to authority. There is something analogous to political parties in all intellectual activity; opinion divides, more or less definitely, into opposing groups, and each side is stimulated by the opposition of the other to define, corroborate, and amend its views, with the purpose of justifying itself before the constituency to which it appeals. What we need is not that controversy should disappear, but that it should be carried on with sincere and absolute deference to the standard of truth. A just resentment is not only a needful stimulus to aggressive righteousness, but has also a wholesome effect upon the mind of the person against whom it is directed, by awakening a feeling of the importance of the sentiments he has transgressed. On the higher planes of life an imaginative sense that there is resentment in the minds of other persons performs the same function that physical resistance does upon the lower.[70] It is an attack upon my mental self, and as a sympathetic and imaginative being I feel it more than I would a mere blow; it forces me to consider the other’s view, and either to accept it or to bear it down by the stronger claims of a different one. Thus it enters potently into our moral judgments. “Let such pure hate still underprop Our love that we may be Each other’s conscience.”[71] I think that no one’s character and aims can be respected unless he is perceived to be capable of some sort of resentment. We feel that if he is really in earnest about anything he should feel hostile emotion if it is attacked, and if he gives no sign of this, either at the moment of attack or later, he and what he represents become despised. No teacher, for instance, can maintain discipline unless his scholars feel that he will in some manner resent a breach of it.