But we must approach the nature of parental duty more closely, and the following reflections may put us in the way: No man can attain the intellectual aims of life without assistance. A scientist inhabiting a desert island and limited to his own mental resources could make little headway. The scientist of to-day utilizes the accumulated labors of all the generations of scientists that have preceded him, and depends for the value of his results on the co-operation and the sifting criticism of his contemporaries. And as no one can get much knowledge without the help of others, so no one is justified in seeking knowledge for his own private pleasure, or in seeking the kind of knowledge that happens to pique his vanity. For instance, it is a violation of intellectual duty to spend one's time in acquiring out-of-the way erudition which is useful only for display. The pursuit of knowledge is a public not a private end. Every scholar and man of science is bound to enlarge as far as he can the common stock of truth, to add to the scientific possessions of the human race. But in order to do this he must question himself closely, that he may discover in what direction his special talent lies, and may apply himself sedulously to the cultivation of that. For it is by specializing his efforts that he can best serve the general interests of truth. The same holds good with respect to the pursuit of social ends--e. g., the correction of social abuses and the promotion of social justice. The reformer of to-day stands on the shoulders of all the reformers of the past, and would have little prospect of success in any efforts he may make without the co-operation and criticism of numerous co-workers. Nor, again, is it right for him to take up any and every project of reform that may happen to strike his fancy. He ought rather to consider what particular measures under existing circumstances are most likely to advance the cause of progress, and in what capacity he is specially fitted to promote such measures. Justice and truth are public, not private ends. The highest aim of life for each one is to offer that contribution which he, as an individual, is peculiarly fitted to make toward the attainment of the public ends of mankind. The individual when living only for himself, absorbed in his private pleasures and pains, is a creature of little worth; and his existence is of little more account in the scheme of things than that of the summer insects, who have their day and perish. But the individual become the organ of humanity acquires a lasting worth, and his individuality possesses an inviolable sanctity. The sacredness of individuality in the sense just indicated is a leading idea of ethics--perhaps it would not be too much to say, the leading idea.