The mind of genius is among other minds what the carbuncle is among precious stones: it sends forth light of its own, while the others reflect only that which they have received. The relation of the genius to the ordinary mind may also be described as that of an idio-electrical body to one which merely is a conductor of electricity. The mere man of learning, who spends his life in teaching what he has learned, is not strictly to be called a man of genius; just as idio-electrical bodies are not conductors. Nay, genius stands to mere learning as the words to the music in a song. A man of learning is a man who has learned a great deal; a man of genius, one from whom we learn something which the genius has learned from nobody. Great minds, of which there is scarcely one in a hundred millions, are thus the lighthouses of humanity; and without them mankind would lose itself in the boundless sea of monstrous error and bewilderment. And so the simple man of learning, in the strict sense of the word--the ordinary professor, for instance--looks upon the genius much as we look upon a hare, which is good to eat after it has been killed and dressed up. So long as it is alive, it is only good to shoot at. He who wishes to experience gratitude from his contemporaries, must adjust his pace to theirs. But great things are never produced in this way. And he who wants to do great things must direct his gaze to posterity, and in firm confidence elaborate his work for coming generations. No doubt, the result may be that he will remain quite unknown to his contemporaries, and comparable to a man who, compelled to spend his life upon a lonely island, with great effort sets up a monument there, to transmit to future sea-farers the knowledge of his existence. If he thinks it a hard fate, let him console himself with the reflection that the ordinary man who lives for practical aims only, often suffers a like fate, without having any compensation to hope for; inasmuch as he may, under favorable conditions, spend a life of material production, earning, buying, building, fertilizing, laying out, founding, establishing, beautifying with daily effort and unflagging zeal, and all the time think that he is working for himself; and yet in the end it is his descendants who reap the benefit of it all, and sometimes not even his descendants. It is the same with the man of genius; he, too, hopes for his reward and for honor at least; and at last finds that he has worked for posterity alone. Both, to be sure, have inherited a great deal from their ancestors.