英语寓言故事-The Cage Bird and the Bat

A singing bird was confined in a cage which hung outside a window,
and had a way of singing at night when all other birds were asleep.
One night a Bat came and clung to the bars of the cage, and asked
the Bird why she was silent by day and sang only at night. "I have a
very good reason for doing so," said the Bird. "It was once when I was
singing in the daytime that a fowler was attracted by my voice, and
set his nets for me and caught me. Since then I have never sung except
by night." But the Bat replied, "It is no use your doing that now when
you are a prisoner: if only you had done so before you were caught,
you might still have been free."

"Precautions are useless after the crisis."