Diablo took one of his long, catlike steps, and paused without bringing up his other foot. In vain Bull spoke to him, softly, steadily. Diablo took another step, quickened to a soft trot, and stopped suddenly. That weight on his back failed to leave him. He began to tremble violently. Bull felt the sudden thundering of the great heart beneath the pressure of his knee. To the stallion, this man had been a friend, a constant companion. The touch of his hand was pleasant. Pleasanter still was the continual deep murmur of the voice, reassuring, telling him of a superior and guardian mind looking out for his interests. Now that hand was stroking his sleek neck and that voice was steadily in his ear. But the position was the most hated one. To be sure, there was no saddle, no cutting, binding cinch, no drag of cruel Spanish curb to control his head, no tearing spurs to threaten him. But his flanks twitched where the spurs had dug in many a time, and he panted, remembering the cinches. Those memories built up a panic. He became unsure. The voice reached him less distinctly. Moreover it was a strange time of the evening. The light of the day was nearly done; the moon was barely up, and all things were ghostly and unreal in that slant light. Something of all that went through the mind of Diablo was understood by Bull Hunter. It was telegraphed to him by the twitching and vibration of great muscles, by the stiff arching of the neck, and the snorting breathing. But he was beginning to forget fear. The stallion danced lightly forward, and as the wind struck the face of Bull Hunter he suddenly rejoiced. This was what he had dreamed of, to be carried thus lightly, easily. The weight that had crushed other horses was nothing to Diablo. It made him feel buoyant. He became tinglingly alert. On the back of Diablo not a horse of the mountains could overtake him if he fled; and not a man of the mountains could escape him if he pursued on the back of the stallion. That thought had hardly formed in his excited mind when Diablo sprang, cat-footed, to one side. It made Bull Hunter sway, and he naturally sought to preserve his balance by gripping the powerful barrel of the horse with his knees. But at the first touch of the knee Diablo went suddenly mad. Exactly what he did Bull Hunter never knew. Indeed, it seemed that Diablo left his feet, shot a dizzy height into the air, and at the crest of his rise did three or four things at once. At any rate, as the stallion landed, Bull pitched from the arched back and hurtled forward and to the right side. He landed heavily against the ground, his head striking a small rock; and he lay there a moment, stunned. Far off he heard Tod shrilling at him, "Bull! Are you hurt?" He gathered himself together and arose, "I'm all right. Stay where you are!" "Don't try him again. He'll kill you, Bull!" "Maybe. But I'm going to try."