| Quote #4
He had been suddenly jerked from the heart of civilization and flung into the heart of things primordial. (2.1)
Buck experiences a violent shift from the civilized world to the primitive one. He recognizes the extremity of such a change.
| Quote #5
They were savages, all of them, who knew no law but the law of club and fang. (2.1)
The primitivity of the wild extends not just to the dogs, but to the men as well.
| Quote #6
The snow walls pressed him on every side, and a great surge of fear swept through him--the fear of the wild thing for the trap. It was a token that he was harking back through his own life to the lives of his forebears; for he was a civilized dog, an unduly civilized dog, and of his own experience knew no trap and so could not of himself fear it. The muscles of his whole body contracted spasmodically and instinctively (2.12)
Buck retains memories of lives not his own.