NEW DELHI : Describing ' Ramcharitmanas ' as a great work which imbibes the "essence of India", Prime Minister Narendra Modi today released the digital version of a musical production on the epic recorded by All India Radio Praising efforts of the artistes, the Prime Minister said they had performed not just ' sangeet sadhna , but also sanskriti sadhna and sanskaar sadhna' (devotion not just to music, but also to culture and tradition).The Prime Minister described Goswami Tulsidas' Ramcharitmanas as a great epic which contained the "essence of India."He mentioned how the Indians who had travelled to various parts of the world, such as Mauritius, kept alive their link with India over successive generations through the Ramcharitmanas, an official statement said here.Modi, while unveiling the set of digital CDs, said the recordings have been done over a period of 20-22 years and the effort was no small achievement.He also appreciated the role played by All India Radio (Akashvani) in uniting the people and spreading awareness and information in India.He said that he has been informed that AIR has approximately nine lakh hours of audio recordings of various artistes from across the country. He said this was a priceless collection, which should be documented in detail for posterity.According to officials, AIR recordings of Goswami Tulsidas' work which were released today have been sung by many leading singers of Bhopal 'gharana' over several years from 1980 onwards.Minister for Information and Broadcasting Arun Jaitley and Chairman Prasar Bharati Board A Suryaprakash were present on the occasion, the statement added.