“How is it, Theo wondered, that a piece of paper - a letter, a photo, a ticket stub, a sketch, a painting - is suddenly transformed by placing it in four bits of wood beneath a pane of glass? What does it mean that we place permanent boundaries around transient moments? What does it say of humankind that we take such trouble to freeze specific memories, that we devote such energy to capturing and preserving the "minute particulars" of our lives?”