The Alwars (also spelled Azhwars) are a group of 12 ancient Vaishnava saints who lived in Tamil Nadu and are famous for their poetry in praise of Vishnu. The 4000 verses of the Alwars were compiled by the Vaishnava Acharya Nathamuni into a book called the Naalayira Divya Prabhandam, which is considered by many to be the "Dravida Veda", or South Indian Veda. It is the principles and beliefs embodied in the Alwars' poems that Nathamuni used to found what we now call the Sri Vaishnava sect (of which I'm a member).
In addition to the Naalayira Divya Prabandham, however, Nathamuni is said to have also composed at least two other works: a work on logic called the Nyaya Tattva and a work in Yoga called the Yoga Rahasya. (He's often credited with the Purusha Nirnaya, although that's sometimes ascribed to his grandson Yamunacharya whom I discuss here.) These works have lost for centuries, but if you go to a bookstore, you may find a book called "Nathamuni's Yoga Rahasya" by T. Krishnamacharya!
For those who don't know, T. Krishnamacharya is one of the fathers of modern Yoga; he was the teacher of B.K.S. Iyengar, founder of the well- known Iyengar Yoga. What is not as well-known is where the techniques of Iyengar Yoga come from. You see, T. Krishnamacharya was a descendant of Nathamuni, and he claims that he had a dream where Nathamuni told him to go to Alwar Thirunagari, the town where Nathamuni received the poems of the Alwars as I discuss here. When he went there, he claims to have experienced a trance where Nathamuni taught him the verses of his lost work, the Yoga Rahasya. That's the purported origin of the verses published in T. Krishnamacharya' book "Nathamuni's Yoga Rahasya".
Now some people doubt T. Krishnamacharya's claims; his son T.K.V. Desikachariar suggests that the book may have been his father's own composition:
“My father never acknowledged that he discovered anything even when I have seen that it was he who discovered. He has discovered postures but he would say that it was his teacher who taught him. Rarely has he said that it was his “original” work.... I tend to think that the Nathamuni’s Yoga Rahasya that he taught us is quite likely to be a combination of his own commentary and the lessons he received though he would not accept it.”
But in this essay Desikachariar says that it's genuinely the work Nathamuni:
The Yoga-Rahasya has unfortunately never been published but there is enough proof to be sure that Nathamuni is definitely the author.
My question is, has anyone examined the Sanskrit verses in Krishnamacharya's book and determined whether they're the work of Nathamuni? Like does the style of the Sanskrit match Nathamuni's era?
And what is Desikachariar alluding to when he says there's "enough proof"?