For a long time after his rescue, Buck did not like Thornton to get out of his sight. From the moment he left the tent to when he entered it again, Buck would follow at his heels. His transient masters since he had come into the Northland had bred in him a fear that no master could be permanent. He was afraid that Thornton would pass out of his life as Perrault and François and the Scotch half-breed had passed out. Even in the night, in his dreams, he was haunted by this fear. At such times he would shake off sleep and creep through the chill to the flap of the tent, where he would stand and listen to the sound of his master’s breathing.

But in spite of this great love he bore John Thornton, which seemed to bespeak the soft civilizing influence, the strain of the primitive, which the Northland had aroused in him, remained alive and active. Faithfulness and devotion, things born of fire and roof, were his; yet he retained his wildness and wiliness. He was a thing of the wild, come in from the wild to sit by John Thornton’s fire, rather than a dog of the soft Southland stamped with the marks of generations of civilization. Because of his very great love, he could not steal from this man, but from any other man, in any other camp, he did not hesitate an instant, while the cunning with which he stole enabled him to escape detection.

His face and body were scored by the teeth of many dogs, and he fought as fiercely as ever and more shrewdly. Skeet and Nig were too good-natured for quarrelling—besides, they belonged to John Thornton; but the strange dog, no matter what the breed or valor, swiftly acknowledged Buck’s supremacy or found himself struggling for life with a terrible antagonist. And Buck was merciless. He had learned well the law of club and fang, and he never forewent an advantage or drew back from a foe he had started on the way to Death. He had lessoned from Spitz, and from the chief fighting dogs of the police and mail, and knew there was no middle course. He must master or be mastered; while to show mercy was a weakness. Mercy did not exist in the primordial life. It was misunderstood for fear, and such misunderstandings made for death. Kill or be killed, eat or be eaten, was the law; and this mandate, down out of the depths of Time, he obeyed.

He was older than the days he had seen and the breaths he had drawn. He linked the past with the present, and the eternity behind him throbbed through him in a mighty rhythm to which he swayed as the tides and seasons swayed. He sat by John Thornton’s fire, a broad-breasted dog, white-fanged and long-furred; but behind him were the shades of all manner of dogs, half-wolves and wild wolves, urgent and prompting, tasting the savor of the meat he ate, thirsting for the water he drank, scenting the wind with him, listening with him and telling him the sounds made by the wild life in the forest, dictating his moods, directing his actions, lying down to sleep with him when he lay down, and dreaming with him and beyond him and becoming themselves the stuff of his dreams.

So peremptorily did these shades beckon him, that each day mankind and the claims of mankind slipped farther from him. Deep in the forest a call was sounding, and as often as he heard this call, mysteriously thrilling and luring, he felt compelled to turn his back upon the fire and the beaten earth around it, and to plunge into the forest, and on and on, he knew not where or why; nor did he wonder where or why, the call sounding imperiously, deep in the forest. But as often as he gained the soft unbroken earth and the green shade, the love for John Thornton drew him back to the fire again.

Thornton alone held him. The rest of mankind was as nothing. Chance travellers might praise or pet him; but he was cold under it all, and from a too demonstrative man he would get up and walk away. When Thornton’s partners, Hans and Pete, arrived on the long-expected raft, Buck refused to notice them till he learned they were close to Thornton; after that he tolerated them in a passive sort of way, accepting favors from them as though he favored them by accepting. They were of the same large type as Thornton, living close to the earth, thinking simply and seeing clearly; and ere they swung the raft into the big eddy by the saw-mill at Dawson, they understood Buck and his ways, and did not insist upon an intimacy such as obtained with Skeet and Nig.

For Thornton, however, his love seemed to grow and grow. He alone among men could put a pack upon Buck’s back in the summer travelling. Nothing was too great for Buck to do, when Thornton commanded.