When one read the book, the other copied it in their own writing and sewed threads in a braid along each edge, so that it was bound. When the book is done, you place it in the first corner, and when another is done, you place it next to it, until three walls are lined with books wedged in too tight for space between. As a row is filled along three walls, one starts another row directly, on top of the previous row. Each book has three dimensions: when it is open (1), when it is written (2), and when it is read (3).