Throughout the sixteenth century it was argued by many that the mass-distribution of cheap literature, chiefly the 'romances of chivalry' favoured by Quixote, were a potentially dangerous influence on the minds of their readers. The emergence of printing and widespread literacy meant that previously protected portions of the populace, such as the working class and women, were able to read a wide variety of material for themselves, instead of being read to from a strict canon of 'improving' literature selected by their social superiors.
Learned scholars and respected churchmen such as Pedro de la Vega attacked the chivalrous tales of knights and damsels as encouraging violence and promiscuity among their impressionable readers. The fictive insanity which overwhelms Don Quixote was not just a source of comedy, but represented (and, arguably, ridiculed) fears which were all too real for many of Cervantes' contemporaries and, indeed, continue to this day in ongoing debates over the potential effects of violent cinema or video-games.
Cervantes' huge knowledge of chivalric romances is shown by the many references to their stories and characters made throughout Don Quixote. Among the most important of these, and Quixote's chief rolemodel both in adopting his knightly title as well as other things, is Amadis de Gaula. A landmark chilvaric romance it passed through the hands of many authors, being rooted in earlier legends, before being drawn together and published by Garci Rodríguez de Montalvo in the early 16th century. Several direct parallels in later chapters suggest that Amadis was one of the chief targets of Don Quixote's satire.
For an ongoing transcription and analysis, explore translator Sue Burke's blog.
Online edition of Robert Southey's abridged English translation (1803)
The concept of insanity partly or wholly relieving a person of responsibility for a crime has been a constant and controversial topic of debate since antiquity, finding its way into the practice of various cultures at various times throughout history. While Quixote often commits numerous acts of violence throughout his adventures, showing several times that he is quite capable of killing those his madness casts as enemies, he is never officially punished or incarcerated for his crimes.
A summarised History of the Insanity Defense at the Online Encyclopedia of Criminal Justice