A favor is remembered
One day when I was in college, I wanted to do something but couldn't because I had a 3 hour job to do at my fraternity house..
Levi Kettle took my duty. Never asked anything in return. I knew that Levi was a nice guy, but he wasn't one of my best friends or anything. I would see him in the hall, and at fraternity functions, but we didn't usually run around together. I don't remember ever doing any big favors for him. I remember trying to negotiate a trade, but he wouldn't hear of it. As far as I can tell, this was just a totally selfless act.
I don't remember what it was that I wanted to do that night. I don't remember who I was with, I don't remember the weather, I don't remember the time of year. I don't remember if I had fun. 12 Years later, the only mark left from that night is the one left by Levi's selfless favor.
Selflessness is a rare virtue these days.