Booking Through Thursday: Useful

From Booking Through Thursday, here’s this week’s question:

What’s the most useful book you’ve ever read? And, why?

This is one of those semi-embarrassing answers, and I’m just going to say it. We’re all friends here, right?
For me, probably the most useful book I’ve ever read is How to Win Friends and Influence People by Dale Carnegie.
I always cringe at that title, because it makes the book sound like a way to manipulate people and trick them into liking you. And the book is so not that.
And for a painfully shy 17-year-old (lo, those many years ago), this book was a godsend.
It contains amazing truths, including (my favorite):
To be considered a great conversationalist, ask the other person about him/herself and then listen.
Egads! Who knew it could be that easy?!