"It is a science," said Don Quixote, "that comprehends in itself all or most of the sciences in the world, for he who professes it must be a jurist, and must know the rules of justice, distributive and equitable, so as to give to each one what belongs to him and is due to him. He must be a theologian, so as to be able to give a clear and distinctive reason for the Christian faith he professes, wherever it may be asked of him. He must be a physician, and above all a herbalist, so as in wastes and solitudes to know the herbs that have the property of healing wounds, for a knight-errant must not go looking for some one to cure him at every step. He must be an astronomer, so as to know by the stars how many hours of the night have passed, and what clime and quarter of the world he is in. He must know mathematics, for at every turn some occasion for them will present itself to him; and, putting it aside that he must be adorned with all the virtues, cardinal and theological, to come down to minor particulars, he must, I say, be able to swim as well as Nicholas or Nicolao the Fish could, as the story goes; he must know how to shoe a horse, and repair his saddle and bridle; and, to return to higher matters, he must be faithful to God and to his lady; he must be pure in thought, decorous in words, generous in works, valiant in deeds, patient in suffering, compassionate towards the needy, and, lastly, an upholder of the truth though its defence should cost him his life. Of all these qualities, great and small, is a true knight-errant made up; judge then, Senor Don Lorenzo, whether it be a contemptible science which the knight who studies and professes it has to learn, and whether it may not compare with the very loftiest that are taught in the schools."
-Es una ciencia -replicó don Quijote- que encierra en sí todas o las más ciencias del mundo, a causa que el que la profesa ha de ser jurisperito, y saber las leyes de la justicia distributiva y comutativa, para dar a cada uno lo que es suyo y lo que le conviene; ha de ser teólogo, para saber dar razón de la cristiana ley que profesa, clara y distintamente, adondequiera que le fuere pedido; ha de ser médico y principalmente herbolario, para conocer en mitad de los despoblados y desiertos las yerbas que tienen virtud de sanar las heridas, que no ha de andar el caballero andante a cada triquete buscando quien se las cure; ha de ser astrólogo, para conocer por las estrellas cuántas horas son pasadas de la noche, y en qué parte y en qué clima del mundo se halla; ha de saber las matemáticas, porque a cada paso se le ofrecerá tener necesidad dellas; y, dejando aparte que ha de estar adornado de todas las virtudes teologales y cardinales, decendiendo a otras menudencias, digo que ha de saber nadar como dicen que nadaba el peje Nicolás o Nicolao; ha de saber herrar un caballo y aderezar la silla y el freno; y, volviendo a lo de arriba, ha de guardar la fe a Dios y a su dama; ha de ser casto en los pensamientos, honesto en las palabras, liberal en las obras, valiente en los hechos, sufrido en los trabajos, caritativo con los menesterosos, y, finalmente, mantenedor de la verdad, aunque le cueste la vida el defenderla. De todas estas grandes y mínimas partes se compone un buen caballero andante; porque vea vuesa merced, señor don Lorenzo, si es ciencia mocosa lo que aprende el caballero que la estudia y la profesa, y si se puede igualar a las más estiradas que en los ginasios y escuelas se enseñan.