What other modern novel takes on the issues of mental health and conformity so well? Many novels have taboos in them, but Kesey's entire story is taboo, and we as readers are allowed to live inside that world for a little while. I would say the fearlessness with which the author deals with these topics and the way in which he presents them has made this into a modern classic.
This modern classic is more timely than ever! About a year ago a prominent psychologist remarked that anyone who is realistic nowadays about the world we live in will be diagnosed as clinically depressed. So, one who is realistic now is mentally ill....Interesting, is it not?
Kesey's work has long brought into question "What is insane?" Is it insane to refuse to conform to what one knows to be dehumanizing and controlling of one's individuality? In this society of politicos, it would seem that Kesey's work is even more relative now than ever. A classic, indeed.
I remember vividly my teacher from sophomore year of high school explaining the answer to this question, and ironically she said the answer is always the same (no matter what literary work is in question). Why does any literary work receive the title of "classic"? The answer, according to Miss Campbell, is the following: The piece of literature has stood the test of time, plain and simple. Here we are six decades later and One Flew Over the Cuckoo's Nest is (often) required reading for high school students everywhere.
Written in 1959 and published in 1962, One Flew Over the Cuckoo's Nestcertainly does what the first two answerers described so eloquently. There was a definite stereotype given to those who were mentally ill in the late fifties. This novel (and subsequent movie) did a lot to change that inappropriate stereotype. I always equated Kesey along the lines of a modern Dorthea Dix, actually. Or perhaps that's going a bit too far. Still, he certainly did a lot to expand the mind of the public to the plight of the mentally ill. In my opinion, the subsequent movie was able to achieve even more in that it reached the segment of the public who preferred not to read. We are all still reading, still watching, and still feeling that jolt of a very tragic ending to this very day.
The previous answerer touches on many good points concerning Ken Kesey's modern classic, One Flew Over the Cuckoo's Nest. The characters that Kesey creates, particularly Randall P. McMurphy and Chief Brombden, are rich in originality and depth. The story is superb on two levels: that of McMurphy and his attempts to maintain his individuality in the mental ward; and the social statements made concerning America's ever-conforming society of the late 1950s. The fact that it spawned such a high-quality film adaptation is another reason that the novel still holds such high interest, and Jack Nicholson's portrayal of McMurphy further brings the novel's character to life upon re-reading. Also, the title ranks with the best of all-time.
The answer to this will depend on who is receiving the question. For my bet, I would say that Kesey's work is so profound because it forced social settings to reexamine what does it mean to be mentally ill. For so long, mental illness was seen as individual problems, conditions for which society could only shun and deny its presence. Kesey's characterizations and his depiction of an institutional setting that lacked individual differentiation and compassion allowed people to reflect on how to provide better care to individuals who are in dire need. The other implication that arises from the work is the idea of what determines "sane" or "insane." In examining the different characterizations offered, in particular McMurphy, there is much in way of examination of who is sane and who is not. In Nurse Ratched's compulsive manner regarding her rules, the reader begins to reconfigure the meaning of insanity.