Look and See which way the wind blows before you commit yourself

Once A Bat fell to the ground and was caught by a Weasel, and was just going to be killed and eaten when it begged to be let go. The Weasel said he couldn't do that because he was an enemy of all birds on principle.

"Oh, but," said the Bat, "I'm not a bird at all: I'm a mouse." So you are," said the Weasel, "now I come to look at you": and he let it go. Sometime after this the Bat was caught in just the same way by another Weasel, and, as before, begged for its life. "No," said the Weasel," I never let a mouse go by any chance." "But I'm not a mouse," said the Bat; "I'm a bird." "Why, so you are," said the Weasel; and he too let the Bat go.