It may be objected that the principle of selection has been reduced to methodical practice for scarcely more than three-quarters of a century; it has certainly been more attended to of late years, and many treatises have been published on the subject; and the result has been, in a corresponding degree, rapid and important.

But it is very far from true that the principle is a modern discovery.

I could give several references to works of high antiquity, in which the full importance of the principle is acknowledged.