A lot of great books, but it's unclear to me that most of these are actually "undervalued." Check out the blurb on the back cover of Philosophical Investigation

A lot of great books, but it's unclear to me that most of these are actually "undervalued." Check out the blurb on the back cover of Philosophical Investigations, for example: Immediately upon its posthumous publication in 1953, Ludwig Wittgenstein's Philosophical Investigations was hailed as a masterpiece, and the ensuing years have confirmed this initial assessment. Today it is widely acknowledged to be the single most important philosophical work of the twentieth century. Drawing on the Right Side of the Brain has had a huge impact. From Amazon: "Translated into more than seventeen languages, Drawing on the Right Side of the Brain is the world's most widely used drawing instruction book." Same with The Inner Game of Tennis -- it was groundbreaking when it came out in 1972 and had a huge impact not just on tennis, or even sports generally, but on musicians, artists, performers, or anything with a critical mental game. Back when I was working on my music degree it was required reading. Is it possible that the author thinks these books are undervalued simply because many of them were released a while ago (when he was young or not yet born) and thus they aren't currently being hyped and/or in the limelight? That, or perhaps they're simply not that popular within the author's social circle?