Describe what he means by these terms-Do you have any objections to his theory?

Nietzche discussion

Nietzsche’s fundamental insight or assertion seems to be that in order to understand morality we must look at history and human culture.

For him morality is not natural in the sense of already being there but is created by humans and evolves.

His example is the evolution of what he calls master and slave morality. Describe what he means by these terms. Do you have any objections to his theory?