Stone lasts, it's permanent-- it seems permanent at least, to most of us by a human life scale. We'll think about the way touch wears stones down, and smooths them out, and makes them decay over long periods of time. This too is part of the process. Stones become sites for memory, places to remember the past. And this is not just an intellectual exercise, some sort of invisible thing we hold in our head. But it becomes something our bodies do-- we touch these stones. We touch the past through touching these stones. And this is part of what becomes the ritualized processes in religion is that we use our bodies, we use our sensual bodies, to do things in the world, in this physical world. And that's how we enact memory, and that's how we enact our connection with those who have gone on before us.