The Brihat (the great) Yoga Vasishta or Yoga Vasishta Maha Ramayana as it is also called, is a work of about 32,000 Sanskrit couplets, traditionally attributed to Valmiki, the author of Srimad Ramayana. It is a dialogue between Sage Vasishta and Sri Rama, during which Advaita (the doctrine of non-duality) in its pure form of ajatavada (theory of non-origination) is expounded, with illustrative stories in between. This vast work was abridged some centuries ago by Abhinanda Pandita, a Kashmiri scholar, into 6,000 couplets, which go by the name of Laghu Yoga Vasishta. This is a masterpiece in itself, like the original Brihat.
Bhagavan Sri Ramana Maharshi used to refer to Yoga Vasishta frequently and has even incorporated six couplets from it in His Supplement to Forty Verses (verses 21 to 27).
A further condensation of this work was made long ago, by an unknown author, into about 230 couplets, divided into ten chapters, as Yoga Vasishta Sara (Essence of Yoga Vasishta). By making this condensation the author has rendered a great service to all sadhaks. This is indeed a goldmine fit for repeated reading and meditation. pp.29