In one word, why are used book sales such an important part of my learning?

Serendipity.

I always find great books I wasn’t looking for. When I’m looking for a book to help me learn something, that’s a known unknown.

But serendipity can lead me to an unknown unknown. It can lead me to learn something I wasn’t even aware that I needed to learn.

Which book in this stack that I picked up last week does that apply to? I don’t know yet. But I’m excited to find out.