The line that kindness takes a moment but means the world turns out to be an understatement: across a run of experiments, the people performing small kind acts consistently underestimated how much they landed, because givers fixate on the gesture while recipients feel the warmth

Kindness takes a moment but means the world is the sort of line that ends up printed on a tote bag, agreeable and weightless. What is worth noticing is that psychologists have spent the last few...