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.

In rude and barbarous periods of English history choice animals were often imported, and laws were passed to prevent their exportation: the destruction of horses under a certain size was ordered, and this may be compared to the "roguing" of plants by nurserymen.

The principle of selection I find distinctly given in an ancient Chinese encyclopaedia.