Concept
Enough
4 books in the library reach for this idea - each in its own way. When independent authors converge on one concept, it usually deserves attention.
It Doesn't Have to Be Crazy at Work
How this book uses it: A radical concept - at some point, you have enough profit, enough growth, enough market share. Stop chasing more.
The Pathless Path
How this book uses it: The threshold of money, status, and security that enables contentment. Most people never define it and therefore never reach it.
The Psychology of Money
How this book uses it: Knowing when to stop pursuing more. Without it, you risk what you have for what you don't need.
Your Money or Your Life
How this book uses it: The sweet spot where you have what you need and value, without excess. More ≠ better past this point.