"It does because it has to," said the Doctor. "Don’t think of books. Think of a mirrored ball, which holds a complete image of the universe, yet is very simple. The ‘brain’ of the monad, then, is a mechanism whereby some rule of action is carried out, based upon the stored state of the rest of the universe. Very crudely, you might think of it as like one of those books that gamblers are forever poring over: let us say, ‘Monsieur Belfort’s Infallible System for Winning at Basset.’ The book, when all the verbiage is stripped away, consists essentially of a rule—a complicated one—that dictates how a player should act, given a particular arrangement of cards and wagers on the basset-table. A player who goes by such a book is not really thinking, in the higher sense; rather, she perceives the state of the game—the cards and the wagers—and stores that information in her mind, and then applies Monsieur Belfort’s rule to that information. The result of applying the rule is an action—the placing of a wager, say—that alters the state of the game. Meanwhile the other players around the table are doing likewise—though some may have read different books and may apply different rules. The game is, au fond , not really that complicated, and neither is Monsieur Belfort’s Infallible System; yet when these simple rules are set to working around a basset-table, the results are vastly more complex and unpredictable than one would ever expect. From which I venture to say that monads and their internal rules need not be all that complicated in order to produce the stupendous variety, and the diverse mysteries and wonders of Creation, that we see all about us."