This beautiful concept is called ‘transactive memory’. This is the observation that we don’t just store information in our minds or in specific places, we store memories and understanding in the minds of the people we love. You don’t need to remember your child’s emotional relationship to her teacher because you know your wife will. You don’t remember how to use the remote because you know your daughter will. I have never learned to make bread because my mom does it for me. Little bits of ourselves reside in other people’s minds.
You know when one half of a long marriage dies and its surviving partner says that some part of them has died along with their spouse. According to Wagner this is true. Everything you’ve stored in your partner’s brain dies with them.