This time it burned suddenly clear and large and very bright, away off to the left of him where he had by daylight noticed a bare shale slide.

The light seemed to stand in the very center of the slide, no more than a mile away.
William stopped when Casey pulled on the reins he had fashioned from the lead rope, and turned stiffly so that he faced the light.

Casey kicked him gently with his heels to urge him forward, for in spite of what his reason told him about the shale slide his instinct was to go straight to the light.

But William began to shiver and tremble, and to swing slowly away.
Casey tried to prevent it, but the mule came out in William.

He laid his good ear flat along his neck as far as it would go, and took little, nipping steps until he had turned with his tail to the light.