start a conversation with a complete stranger for the hell of it

I remember one time in a bookstore where this old guy (apparently he was a grandfather, looking for a book for grandson, I would learn later) joined me in scanning some Harry Potter releases.
He asked me cheerfully about them. I said they’re excellent, and to his next question, I added that No, you dont really need to start (I clumsily used the term “familiar”) reading the previous installation to enjoy this latest one. He replied “Oh, since familiarity breeds contempt, eh?” (That time, i was my first time to hear that very deep expression.) I laughed and he turned to talk to a companion.
This conversation taught me to be careful how I spent my initial moments with a new friend. That man was really somebody worth knowing. His smartness really can be felt!