But your own books belong to you; you treat them with that affectionate intimacy that annihilates formality. Books are for use, not for show; you should own no book that you are afraid to mark up, or afraid to place on the table, wide open and face down. A good reason for marking favorite passages in books is that this practice enables you to remember more easily the significant sayings, to refer to them quickly, and then in later years, it is like visiting a forest where you once blazed a trail. You have the pleasure of going over the old ground, and recalling both the intellectual scenery and your own earlier self.