The cat will mew, and dog will have his day.
Shakespeare
William Shakespeare (1564–1616), British dramatist, poet. Hamlet, in Hamlet, act 5, sc. 1, l. 292.
One cannot stop a creature from acting according to its nature. Hamlet may refer to Laertes (as the cat), and himself (as the dog whose turn will come). The saying about the dog was proverbial.