With one item in its grasp, it snaps instantly to the next that is suggested by the association of thoughts, in accordance with some intricate web of trails carried by the cells of the brain. Having found one item, moreover, one has to emerge from the system and re-enter on a new path. It can be in only one place, unless duplicates are used one has to have rules as to which path will locate it, and the rules are cumbersome. When data of any sort are placed in storage, they are filed alphabetically or numerically, and information is found (when it is) by tracing it down from subclass to subclass. Our ineptitude in getting at the record is largely caused by the artificiality of systems of indexing. The real heart of the matter of selection, however, goes deeper than a lag in the adoption of mechanisms by libraries, or a lack of development of devices for their use.