Sunscreen works on cloudy days because the rays you can’t feel still reach you. Same with words.

Clouds do not stop what you cannot feel from reaching you. The rays are still arriving, and the burn shows up hours later, which is exactly the shape of a careless comment. Nothing registers in the moment, nobody flinches, and the thing lands anyway and keeps working. Words you would barely remember saying can be the ones somebody is still carrying next month.

Think about the person you are most casual around, probably a sibling or your closest friend. Watch what you say to them for a week and notice what you have been assuming they can absorb.