The Fourth Turning (aka Strauss-Howe generational theory):

The idea that history is not linear but helical, because civilization has its own seasons

Most people are bad at expressing themselves, so don’t interpret their words literally, but rather by what they are most likely to mean. What they are most likely to mean is whatever the best possible interpretation of their words is.

ego is the greatest obstacle to reason.

Cleopatra lived closer in time to the creation of Twitter than to the creation of the Great Pyramid. The T-Rex lived closer in time to us than to the Stegosaurus.

Gurwinder's Defibrillator (to restart your heart when you’re out of empathy):

Everyone is an ape adrift in an alien world, born into a struggle they did not choose, bullied by impulses they cannot control, searching for answers they will not find, and condemned to a fate they do not deserve.

Go easy on them.

Just because someone is intelligent, doesn’t mean their intelligence is pursuing intelligent goals. It’s possible to devote a genius-level intelligence to justifying idiotic opinions and behaviors. Tragically, a common fate of intellectuals.

Good character is not about maximizing virtues but moderating them: to be sensitive without being fragile, confident without being cocky, steadfast without being stubborn, driven without being reckless, focused without being obsessed.