Jack Scott writes

A Covenant with Mice

No, my children, 
you can’t grow. 
You must stay kittens 
and eat fish, 
a kind of vegetarian crow. 
They say the taste of blood corrupts, 
and alley rats sometimes eat cats, 
a covenant with mice. 
In is final; 
out is no.

Cat Catching a Mouse -- Ohara Koson