To conclude, all other living creatures live orderly and well, after their own kind: we see them flock and gather together, and ready to make head and stand against all others of a contrary kind: the lions as fell and savage as they be, fight not with one another: serpents sting not serpents, nor bite one another with their venomous teeth: nay the very monsters and huge fishes of the sea, war not amongst themselves in their own kind: but believe me, man at man's hand receiveth most harm and mischief.

Pliny The Elder