I can modestly say that this book towers over all others--to read it is to have your thinking seriously upgraded and your heart expanded to cosmic dimensions. Here's our class examination from the most recent trip through it, verse by verse of Narayana Guru's Hundred Verses of Self-Instruction, as elucidated by Nitya Chaitanya Yati.
The core is the karu in Malayalam, the central numinous principle symbolized by the heart.
From chapter 5 on I have included Nataraja Guru's commentary, and from chapter 13 Nitya's "short version": Neither This Nor That But...Aum. Also beginning in chapter 13, there is a fine commentary by Jake (James de Ste. Croix) who attended the class. Chapter 13 includes my apology for attempting to teach this masterwork.