A child often asks questions whose depth is amazing. "Where was I before I was born? Where will I go when I die? Why do people have to suffer?"Students also sometimes ask questions whose depth is such that teachers have trouble coming up with answers. That is what happened to me on January 31, 1984 as I was teaching my Introduction to Economics course at Maisonneuve College in Montreal, Canada. Suddenly a student raised her hand and asked me with great sincerity: "Sir, what makes the world go round, love or money?" Taken aback by the simplicity and depth of her question, I remained silent for a few seconds, made a few comments and, remembering the lessons I had learned from the American psychotherapist Carl Rogers, asked them what they thought the answer was judging by their own life experience. There ensued a very intense and passionate class discussion that lasted two consecutive lectures.I then went home and wrote What makes the world go round, love or money? a long class handout in which I first presented the highlights of our class discussion and then provided my own answer to the question. More specifically, I reflected on the nature of love, then on the nature and basic functions of money in our present economy, and finally I attempted to come up with my own answer to the question. Afterwards I provided the views of Adam Smith, Karl Marx, Erich Fromm, and Antoine de Saint-Exup ry on this matter. This book reproduces that same class handout, which I rewrote and expanded in Puerto Vallarta, Mexico in January 1986. It includes a 2015 epilogue in which I present Pope Francis' views on whether it is love or money that makes the world go round.