The handwriting on an old shopping list can become more valuable than the items it names.

An old shopping list can outlast everything it referred to. The items are long gone and the handwriting remains, carrying the person more directly than any deliberate keepsake, because it was written without any thought of being kept. What was never meant to be meaningful ages into the most personal thing available.

So be slow to throw away the incidental traces: notes, lists, the margins of things. And be aware that the objects you carefully preserve are rarely the ones that will move someone later. What survives well is usually the unselfconscious, and there is no way to know in advance which piece of it that will be.