Henry Miller:
A book lying idle on a shelf is wasted ammunition. Like money, books must be kept in constant circulation. Lend and borrow to the maximum -- of both books and money! But especially books, for books represent infinitely more than money. A book is not only a friend, it makes friends for you. When you have possessed a book with mind and spirit, you are enriched. But when you pass it on you are enriched threefold.