You know, all is development. The principle is perpetually...

You know, all is development. The principle is perpetually going on. First, there was nothing, then there was something; then-I forget the next-I think there were shells, then fishes; then we came-let me see-did we come next? Never mind that; we came at last. And at the next change there will be something very superior to us-something with wings. Ah! That's it: we were fishes, and I believe we shall be crows.