The meaning of "the whole burden of"

Question

He beat more furiously than ever upon the cage and slipped his great fingers through the bars, trying to reach the Professor, and poured out volumes of ape-chatter.

Why, why did men shoot at him, he asked. He made himself terrible, therefore men ought to love him. That was the whole burden of what the Professor calls its argument.

This is a novel about a gorilla who could speak with a professor. I do not understand the meaning of the sentence below.

That was the whole burden of what the Professor calls its argument

What does "burden" mean in this context?

Does "argument " mean "a quarrel" here?

Answer 1

I suspect the author is making a reference to the "burden of proof" required to presuade someone that an idea is correct. Argument is one method of providing proof to someone you are attempting to convince.

In the passage you describe, the word "argument" has the meaning of "an idea" or maybe "a really convincing story" that "the professor" has given to the gorilla, and the word "burden" has the meaning of the justifications given for the plausibility of that idea or story.