Witnessing kindness in action touches my heart.

There's a reason people well up at very small things — a bus driver waiting while somebody runs half a block, a teenager giving up a seat before being asked.

The size is out of all proportion to the reaction, which suggests we aren't responding to the act. We're responding to the evidence. Something in most people is quietly worried the world is worse than it is, and each of these is a data point against that worry.

Which makes the witnesses part of the transaction.

The driver did one thing. Everybody on the pavement got something out of it, and half of them are marginally more likely to do the same by Thursday.