The term 'NOT EVEN A MOUSE' is a phrase that has been used since the 16th century to express the idea that even the smallest and weakest of creatures should be treated with respect. It is derived from a fable by Aesop, in which a mouse pleads for its life to a cat, saying that even it has done nothing wrong. The phrase is often used to emphasize the importance of treating all living things with kindness and compassion.