How does white fang learn that the" crime of crimes" is not such a crime in certain circumstances

Grey Beaver defends him, this is how he learns that a crime is not a crime under certain circumstances.

"But White Fang knew that he had broken the law of the gods. He had driven his teeth into the sacred flesh of one of them, and could expect nothing but a most terrible punishment. He fled away to Grey Beaver, behind whose protecting legs he crouched when the bitten boy and the boy’s family came, demanding vengeance. But they went away with vengeance unsatisfied. Grey Beaver defended White Fang. So did Mit-sah and Kloo-kooch. White Fang, listening to the wordy war and watching the angry gestures, knew that his act was justified. And so it came that he learned there were gods and gods. There were his gods, and there were other gods, and between them there was a difference. Justice or injustice, it was all the same, he must take all things from the hands of his own gods. But he was not compelled to take injustice from the other gods. It was his privilege to resent it with his teeth. And this also was a law of the gods."