I don't believe that you have to be a cow to know what milk is.

Milk the cow that standeth still

Know yourself. Don't accept your dog's admiration as conclusive evidence that you are wonderful.

Keep a cow, and the milk won't have to be watered but once

Opie, you haven't finished your milk. We can't put it back in the cow, you know.

If you do not milk the cow fully, it falls sick.