In Cervantes' epic, Don Quixote tries to live by the tenets of "courtly love," a concept that was very popular in his era.
David L. Simpson of DePaul University explains courtly love in literartue. He says that, "before it established itself as a popular real-life activity, courtly love first gained attention as a subject and theme in imaginative literature. Ardent knights, that is to say, and their passionately adored ladies were already popular figures in song and fable before they began spawning a host of real-life imitators in the palace halls and boudoirs of medieval Europe. (Note: Even the word "romance"--from Old French romanz--began life as the name for a narrative poem about chivalric heroes. Only later was the term applied to the distinctive love relationship commonly featured in such poems.)"
Courtly love is one of the major themes the Don's adventure and it almost always informs the tone. From the beginning of the Don's adventures to obtain the elusive Dulcenia, his every action is propelled by the concept of courtly love. He battles the "giants" for her (the windmills). He endures scorn and challenges to his manhood for the lady. He travels far and wide, all for the adoration of his supposed "beloved."