Read these lines: "But Buck possessed a quality that made for greatness, imagination. He fought by instinct, but he could fight by head as well. He rushed, as though attempting the old shoulder trick, but at the last instant swept low to the snow and in. His teeth closed on his enemy's left fore leg." How did Buck finally get past his rival's guard?

1. 1. The quoted lines credit imagination, and explain it as fighting by head as well as by instinct. 2. 2. The move described starts as the old shoulder trick, which the rival already knew how to meet. 3. 3. At the last instant Buck goes low instead, and his teeth close on a fore leg, so the first move was a feint. 4. 4. Weight, waiting and outside help are never mentioned in the quoted lines. _Source: The Call of the Wild by Jack London (1903)_