I was thinking about how when two friends are with each other talking, they are in a world of their creation that only they share. Their world has a history, a present, and a future. Events have antecedents and implications specific to them both.
And emotions. They've shared emotions and each emotion is like another bond between them. It will be a part of their memory that only they two share — their own world.
Think about how many worlds we live in.