I shall not weary the reader with proofs of heredity. It would be a waste of words to quote pages of Darwin, Spencer, Weissmann, and Galton for the sake of proving the obvious. Our own observation and common sense will convince us that our traits and qualities of body and mind are inherited.
We know that rabbits do not breed kittens, nor eagles geese, nor apples oranges, nor negroes whites. We know that in all cases where the breed is pure the descent is pure; and we understand that where a black sheep is born into a white flock, or a fair child is born of dark fore-parents, the "sport," as it is called, is due to atavism, or breeding back. Somewhere, near or far, the breed has been "crossed."
But there is one question that has caused a good deal of doubt and perplexity, and, as the answer to that question is not obvious, we will consider it here.
A "sport" is "an individual departure from a type." A sport is a "freak of nature." A genius is a "sport"; and the question we are to answer here is:
How does heredity account for genius?
To make the matter quite clear, and to meet all doubts, we will split our question into two:
1. How is it that genius does not always beget genius?
2. How is it mediocrity does sometimes beget genius?
Take the first question. How is it that genius does not always beget genius? Mr. Galton has disposed of the objection that clever men do not have clever sons by showing that clever men often do have clever sons.
But the fact remains that such men as Shakespeare, Plato, Cæsar, and Socrates never have children as great as themselves.