I'll catch public transport every day but never learn the difference between zones 1 and 2.
I won't remember your age, or your birthday, or what your political stance is
But I'll remember about the time when you were six and you knocked your head on a chair, chipping off half of your brand new buck tooth.
And even the way you shook your head self-deprecatingly after you told me that story and pointed to the filling you have now because of it.
You said that it's invisible but I saw it -- if only because you told me it was there.