What lesson does Thornton teach buck?

John Thornton and Buck's connection goes far beyond the working relationship that Buck had with Francois and Perrault. He respected those men for their understanding of dogs and of nature, but he had no great affection for them. John Thornton is "the ideal master," for he understands Buck without difficulty or confusion. Buck loves him because he shows his need for Buck, repeatedly demonstrating that Buck can help him in ways that others can't. When Buck wins him 1600 dollars or saves him from a deadly rapid, John Thornton is honoring Buck, honoring his power and his loyalty. This loyalty goes beyond the loyalty of the team. Buck depended on those dogs for his life, but he depends on John Thornton for his happiness.

Buck learns the "law of the club" from Red Sweater, he learns about oppression. Thorton teached Buck about love, loyalty, and partnership.