Shrimadh Bhagvad Gita Rahasya, popularly also known as Gita Rahasya or Karmayog Shashtra, is a 1915 Marathi language book authored by Indian social reformer and independence activist Bal Gangadhar Tilak while he was in prison at Mandalay, Burma. It is the analysis of Karma yoga which finds its source in the Bhagavad Gita, a sacred book for Hindus. According to him, the real message behind the Bhagavad Gita is Nishkam Karmayoga (selfless action), rather than Karma Sanyasa (renouncing of actions), which had become the popular message of Gita after Adi Shankara. He took the Mimamsa rule of interpretation as the basis of building up his thesis.