The poetry of the troubadours borrowed nothing from history, mythology, or from foreign manners, and no reference to the sciences or the learning of the schools mingled with their simple effusions of sentiment. This fact enables us to comprehend how it was possible for princes and knights, who were often unable to read, to be yet ranked among the most ingenious troubadours. Several public events, however, materially contributed to enlarge the sphere of intellect of the knights of the _Langue d'oc_. The first was the conquest of Toledo and Castile by Alphonso VI., in which he was seconded by the Cid Rodriguez, the hero of Spain, and by a number of French Provençal knights; the second was the preaching of the Crusades. Of all the events recorded in the history of the world, there is, perhaps, not one of a nature so highly poetical as these holy wars; not one which presents a more powerful picture of the grand effects of enthusiasm, of noble sacrifices of self-interest to faith, sentiment, and passion, which are essentially poetical. Many of the troubadours assumed the cross; others were detained in Europe by the bonds of love, and the conflict between passion and religious enthusiasm lent its influence to the poems they composed. The third event was the succession of the kings of England to the sovereignty of a large part of the countries where the _Langue d'oc_ prevailed, which influenced the manners and opinions of the troubadours, and introduced them to the courts of the most powerful monarchs; while the encouragement given to them by the kings of the house of Plantagenet had a great influence on the formation of the English language, and furnished Chaucer, the father of English literature, with his first models for imitation.