I was riding the subway the other day, and we stopped at a particularly busy stop. A woman, rushing to get on, got trapped by the closing doors across from my seat.

With no hesitation or ceremony, two gentlemen reached for the doors, and forced them open, so she could enter. Nothing was said; it was business as usual.

Then, not one minute later, the train lurched, and an older gentleman standing in front of me lost his footing and started to fall.

Again, with no hesitation, two other people reached out and grabbed his elbows, bracing him to keep him securely upright. He regained his balance and on we went - again with nothing said.