From Aesop's Fables:
A Wolf came upon a Lamb straying from the flock, and felt some compunction about taking the life of so helpless a creature without some plausible excuse; so he cast about for a grievance and said at last, "Last year, sirrah, you grossly insulted me." "That is impossible, sir," bleated the Lamb, "for I wasn't born then." "Well," retorted the Wolf, "you feed in my pastures." "That cannot be," replied the Lamb, "for I have never yet tasted grass." "You drink from my spring, then," continued the Wolf. "Indeed, sir," said the poor Lamb, "I have never yet drunk anything but my mother's milk." "Well, anyhow," said the Wolf, "I'm not going without my dinner": and he sprang upon the Lamb and devoured it without more ado.