A farmer is returning from market, where he bought a she-goat, a wolf and cabbage. On the way home he must cross a river. His boat is little, allowing him to take only one of the three things. He can't keep the she-goat and the cabbage together (because the she-goat would eat it), nor the she-goat with the wolf (because the she-goat would be eaten).
How shall the farmer get everything on the other side (without any harm)?