without looking, describe you shoes. in detail. how many inches long, high, and wide are they? What kind of material lines the back of their tongues? take out a piece of paper and sketch the patterns that marks the soles (no peeking).
How did you do? When I picture my shoes in my head, I can conjure a snapshot or two from different angles that my memory has recorded, but I can't sustain any of these pictures to construct the shoes in much detail. Even if I were to study my shoes for years and years, until I could hold and sustain a picture of my shoes in my memory long enough to exhibit their details, I would not have anything more than a somewhat-reliable still. I might reconstruct some features incorrectly, distort certain points. What's more, I would at best have in that still picture a rough approximation of my shoes at a frozen point in time--I wouldn't have shoes that move, that walk, that go on and off my feet, that touch asphalt and grass and carpet.
Here my meditation partner Descartes asks me: How then, can you be sure you put on the same shoes every morning?
I have no good answer, except for a vague feeling of protest. Why would I want to be sure that I was putting on the same shoes every morning?