I walk past a middle school at lunch every day. Most days we all just carry on with our own work (mine: dog walking, theirs: game playing), but today was different.

As I walked by the school yard, one of the kids kicked a ball over the fence and across the street. She asked if I would throw it back over, apologizing a lot as she did. It’s no real burden for me, so I retrieved it and threw it back over.

Another student asked if I could help retrieve a second ball, and then a third (there wasn’t a fourth). Again, not a problem, so I returned those balls as well. And then he said this:

“You’re so generous! Thank you! If I could pay you $100 I would, but I don’t have any money. Your dog is beautiful and healthy. Have a good day!”

Now, I can’t be sure of what drove him to have that little interaction with me. But I would like to imagine it’s a mixture of these things:

1. Having a very high valuation of time.
2. Having a very low valuation of a dollar.
3. Having an innate sense for the existence of reciprocity.

Which then led him to decide that, knowing that he needed to pay for the use of my expensive time, a compliment to my dog was worth $100.