A great story told by Paul Weiss in Arthur Koestler and J.R. Smythies, eds., Beyond Reductionism (Boston: Beacon Press, 1971), p. 403—
There were two neighbors; one of them contended that the other's cat had stolen and eaten five pounds of his butter; there was a bitter argument and finally they agreed to seek the advice of the rabbi. They went to the rabbi and the owner of the cat said: "It cannot be, my cat doesn't care for butter at all"; but the other insisted that it was his cat and so the rabbi decided: "Bring me the cat." They brought him the cat and the rabbi said: "Bring me the scales." And they brought the scales and he asked: "How many pounds of butter?" "Five pounds." And believe it or not, the weight of the cat was exactly five pounds. So the rabbi said: "Now I have the butter, but where is the cat?"