Ask HN: Books on human nature that changed your interactions

After reading 48 Laws of Power, I started seeing interactions between 1) others & myself, 2) others & others in a completely different light. There were these mental "hooks" I could analyze human interactions through.

Neil Strauss's "Rules of the Game" did something similar.

I'm currently reading Robin Baker's "Sperm Wars" and it's again showing me human interactions through a new light.

So, HN: what are the books that presented new theories / ideas on human nature that has changed the way you view / analyze human interactions?

Why is 48 laws of power BS? There are rules in the book that contradict each other, but it provides a framework for recognizing patterns of human behavior and analyzing it.

Plato's "The Sophist".

Saint-Simon's memoirs.

Neither really for theories as such, the latter for reflections on the the behavior observed.

Since wturner mentions "Blood Rite" let me throw in Vico's "New Science"