What is meant here by the memory library refers to the modern psychological study of inward speech and inward handwriting. This accounts for the existence of inward books and collections of books, and a collection of inward books is obviously a real library. It makes little difference where or how these are kept in the brain. They doubtless imply a library economy at least as different from that of printed and bound books as the books themselves are different from papyrus rolls, clay tablets, or phonographic records, but it is a real collection of books and the psychological study of the place and manner of their housing and the method of their arrangement and prompt service to the owner for his use is not a matter of analogy or figure of speech. The essence of the book is a fixed form of words. The point is that a certain form of words worked into a unity is preserved in exactly that form. The author looks at it as a whole, prunes, corrects, substitutes better words for inferior ones, and generally works over it as a man works over a painting or statue. At the end of the process when the book is finished it is a fixed form of words, a new creation, an individuality. The ordinary habit of thought and conversation does not reach this point of fixed forms of words although in the case of very retentive memories, where the complete verbal form of conversation is remembered, it approaches it. In general men seldom remember the exact phraseology when they listen to a sermon or a story. On the other hand, however, the actor or the professional story teller can summon at will the exact verbal form of a great number of works and each of these works is properly a book. This permanent fixing of form undoubtedly implies some substance in which the words are recorded, but if that substance is the human brain the result is no less a book, a real record in the real substance, than if recorded in outward substance such as stone or ink. The practice of keeping such inward records of exact fixed forms of words is not only the oldest form of record keeping and one extensively practised in illiterate periods, but it is commonly practised in modern life by orators who speak without notes, and as a method for the teaching of children before they learn to read (“memorizing”) as well as afterwards in the schools.