Authors:

Love is an emotion. It can't be seen or touched, and it is experienced differently by everyone, therefore it is difficult to measure.

"Ask a grown-up: how do we measure love?" by Marian Keyes, www.theguardian.com. May 11, 2013.
Love is an emotion. It can't be seen or touched, and it is experienced differently by everyone, therefore it is difficult to measure.