Why did Ian's heart give a sudden lurch at those words? He knew better than to think they were aimed at him. No, the learned professor was merely discoursing on a topic. It could have been any topic - magic or runes or the history of Hogwarts - or love. Right?
So why did Ian want to read more into it? Was he simply asking to be hurt? But he asked the question that was uppermost in his mind and heart anyway.
"Then if you don't know it, how will you recognize it? And how will you get the other person to acknowledge it?"