The River Crossing

A farmer must get a wolf, a goat, and a cabbage across a river. His boat is small and can only carry one item at a time. If left alone, the wolf will eat the goat, and the goat will eat the cabbage. How does the farmer get all three across the river safely?

The farmer first takes the goat across. Then he returns and takes the cabbage, but when he drops off the cabbage, he takes the goat back with him. He then takes the wolf across and leaves it with the cabbage. Finally, he returns to bring the goat across.