Overall, what does Buck learn from his experience of "the law of club and fang" in The Call of the Wild?
The canine hero of Jack London's Call of the Wild, Buck learns that only the strong survive. He also finds that who possesses the club wields the power. Buck comes to realize that humans are the masters of the four-legged beasts: They supply the food for energy and the fire for warmth. He learns to obey his masters, knowing that these two essentials may be withdrawn and replaced by the club. Buck also learns that among the other dogs, the strongest and craftiest are most likely to live the longest. He soon learns the tricks of stealing food and eating quickly. He also finds that working as a team is good for all of the dogs, so he drives the other dogs just as hard as he drives himself.
Overall, what Buck learns from this is that out here in this new world where he is now living, you have to be strong.
Whenever someone is stronger than you (like the man with the club), you have to be patient and do what they say until you can get to be stronger than them.
Buck learns that if you want to survive, you have to learn all the tricks. You have to learn how to steal food without getting caught. You have to learn how to keep warm. You have to learn how not to get killed in a fight.
So basically, Buck is learning that he is in a dog eat dog world where you have to be as strong as you can be to avoid being hurt or even killed.