It is plain, for one thing, that Sancho Panza did not enter into the
original scheme, for had Cervantes thought of him he certainly would not
have omitted him in his hero's outfit, which he obviously meant to be
complete. Him we owe to the landlord's chance remark in Chapter III that
knights seldom travelled without squires. To try to think of a Don
Quixote without Sancho Panza is like trying to think of a one-bladed pair
of scissors.

The story was written at first, like the others, without any division and
without the intervention of Cide Hamete Benengeli; and it seems not
unlikely that Cervantes had some intention of bringing Dulcinea, or
Aldonza Lorenzo, on the scene in person. It was probably the ransacking
of the Don's library and the discussion on the books of chivalry that
first suggested it to him that his idea was capable of development. What,
if instead of a mere string of farcical misadventures, he were to make
his tale a burlesque of one of these books, caricaturing their style,
incidents, and spirit?

In pursuance of this change of plan, he hastily and somewhat clumsily
divided what he had written into chapters on the model of "Amadis,"
invented the fable of a mysterious Arabic manuscript, and set up Cide
Hamete Benengeli in imitation of the almost invariable practice of the
chivalry-romance authors, who were fond of tracing their books to some
recondite source. In working out the new ideas, he soon found the value
of Sancho Panza. Indeed, the keynote, not only to Sancho's part, but to
the whole book, is struck in the first words Sancho utters when he
announces his intention of taking his ass with him. "About the ass," we
are told, "Don Quixote hesitated a little, trying whether he could call
to mind any knight-errant taking with him an esquire mounted on ass-back;
but no instance occurred to his memory." We can see the whole scene at a