Thornton is the ideal master because he has a deep intuitive understanding of Buck that is not based on a transaction. He does not primarily see Buck as an object to be exploited for his own benefit, but as a fellow creature of nature. His relationship with Buck falls into the category of what Audre Lorde in her essay “The Use of the Erotic as Power,” calls “sharing deeply any pursuit” with another. This deep level of understanding (and it is important to note that Lorde uses the term erotic primarily in a non-sexual way) “forms a bridge between the sharers. It reminds/reveals to us that the capacity for joy and deep satisfaction is possible."
While Lorde was discussing a relationship between two people, her notion of the erotic can easily be expanded to Buck and Thornton. When Thornton and Buck are left by the river so Thornton can recover from his frozen feet, they bond in a deep way. Thornton treats his dogs like his children "because he could not help it." Buck, in turn, loves his master's "rough embrace." Thornton thinks of his Buck, “God! you can all but speak!”
Thornton is "the ideal master" because while "other men saw to the welfare of their dogs from a sense of duty and business expediency; he saw to the welfare of his as if they were his own children". Buck's other masters, Francois, Perrault, Charles, and Hal, saw dogs as a means to an end - to do a job, or for personal gain, and although Buck's life with the Judge was comfortable, Buck's relationship with his owners was more detached, "a working partnership...a sort of pompous guardianship...a stately and dignified friendship". Thornton cares for his dogs with all his heart, he sees them as individuals and is truly be concerned for their well-being, creating an environment for mutual respect and growth. He gets close to his dogs. For the first time, Buck experiences "love, genuine, passionate love" (Chapter 6).