Staying with Thornton during the spring, Buck's strength is restored. He plays with Skeet and Nig, Thornton's dogs, and he also loves Thornton, the man who saved his life. He regards Thornton as the ideal master because he looks after his own dogs as if they were his children. Buck adores him, and goes wild with happiness when Thornton touches him or speaks to him. He does not even like to lose sight of Thornton, since he is afraid of losing him.
In spite of his faithfulness and devotion, however, Buck retains the wildness that has been growing in him since he was first kidnapped. If a strange dog appears, he fights fiercely, and always prevails. He never shows any mercy. He also hears the call of his wild nature, and apart from Thornton, he no longer has any ties to the human world. It is only Thornton that draws him back. No task is too great for Buck to do for his master. He is even prepared to jump over a cliff when Thornton, on a whim, tells him to.
Later that year, a man named "Black" Burton picks a quarrel with Thornton at a bar. Burton hits him, and is immediately attacked by Buck. He barely escapes with his life, and as a result of his defense of his master, Buck gets a reputation through all the camps in Alaska. Later in the year, Buck saves Thornton from drowning in a bad stretch of rapids on the Forty Mile River.
That winter, Buck's fame spreads even farther throughout Alaska, when he wins a bet that Thornton makes in a bar. The bet is that Buck can start a sled that weighs a thousand pounds. The test takes place in the street outside the bar, and Buck succeeds in his task, breaking the sled out of the ice and pulling it for one hundred yards. This feat of Buck's wins sixteen hundred dollars for his master. A man then offers to buy Buck for twelve hundred dollars, but Thornton is not interested in selling.
This chapter appears at first to take Buck in a different direction. Up until now, he has been steadily acclimatizing himself to the harsh Arctic environment and reverting to his primitive nature, hearing more and more the call of the wild. Humans mean much less to him than they used to, when he lived on Judge Miller's ranch, and he obeys them only because of the "law of club," that is, the superior power, of man. But now this appears to turn around. With John Thornton, Buck develops a relationship far closer, and more loving, than anything he had known in the civilized world of the Santa Clara Valley. Perhaps the reason London inserted this chapter here is that he wanted to increase the drama of Buck's final rejection of the human world when it takes place in the last chapter. In order to accomplish this, London has to reestablish Buck's links with humans.
Having said that, it should also be noted that Buck is a completely different dog with Thornton than he was when he was merely Judge Miller's pet, all those years ago. Buck is now a dog who has come in from the wild and chooses for the time being to stay with a human companion, rather than being a pet who has known nothing other than comfort and human kindness. Buck remains tough, merciless, supreme. And Thornton is Buck's last link with the human world. He does not extend his love or his trust to other humans, to whom he is indifferent, even disdainful. He has not returned to the state of innocence he was in at Judge Miller's, when he trustingly allowed Manuel to sell him into slavery. And despite his new attachment to Thornton, the call of the wild gets stronger and stronger within him and the claims of man slip away. For a while he lives as it were in two worlds, but it is only his attachment to Thornton that prevents the wild from claiming him completely.
The Call of the Wild: Novel Summary: Chapter 6