It’s a fundamental of all the ancient Cynic, Stoic and Taoist philosophy texts. Here’s my interpretation from the Tao te Ching.
Avoid hubris. Be simple.
Avoid overconfidence – your own and others’. Nothing is certain. No one can tell the future. No one knows everything. Leave room to be wrong. Preserve optionality.
Don’t try to stand out against others.
Accept things as they are and remove complexity.
How to Be
This one is a hard-learned lesson. And it’s the first rule.
It isn’t just about not being boastful. It’s about protecting the downside by not letting your ego trick you that it’s all upside.
Ice Cube said it well: you better check yo’self before you wreck yo’self.