Mentoring taught me more than it taught them

A junior developer once asked me why we use dependency injection. I gave some answer about testability and loose coupling. They nodded. Then they asked: "But why does that matter?"

I didn't have a good answer. I'd been using the pattern for years without really thinking about it.

That's the thing about mentoring. You think you're teaching, but half the time you're discovering gaps in your own understanding. Junior developers ask obvious questions that turn out to be not obvious at all. They haven't learned to stop asking "why" yet.

I wouldn't be where I am without people who took time to explain things to me. So I try to do the same. But honestly? I get as much out of it as they do.