"Neurosis is always a substitute for legitimate suffering": Carl Jung
Aside from reference books, no non-fiction book I own has gotten more repeated use than "The Road Less Travelled" (1978) by M. Scott Peck. His final book, "The Road Less Travelled And Beyond: Spiritual Growth In An Age Of Anxiety" (1997) is a fitting coda, expanding on many of the themes introduced in his earlier work.
Because he was a Jungian, I was favorably inclined toward Peck from the outset. And though not normally drawn to writers with overt ties to organized religion, the way Peck wove Christianity into all his books never distanced me. One of the most memorable sections in "...Beyond" describes what Peck calls the "stages of faith". I clearly recognized myself as someone in stage three; Peck terms this the "materialistic" stage.
For me, wise writers often produce "ouch" insights; you know, the kind that sting a bit. Each time I return to Peck's 1978 debut, I find a new one; many seem to occur when the Jungian and the Christian intersect. In his last book there's this: "Those who object to values being taught fail to see that we have already interjected a basic nihilistic value in to school curricula". What was the last "ouch" insight you pulled from a book?