everything has context
I keep returning to the same idea from different directions: nothing means anything on its own.
A sentence changes when you learn who said it. A photograph changes when you learn what happened the following week. A decision that looked reckless becomes obvious once you know what the person was avoiding.
This is why I document. Not because memory is unreliable, though it is, but because the context arrives later and there has to be something left for it to attach to.