Ribhu, after observing Tapas (penance) for 12 long deva years, is visited by Vishnu in his Varaha avatar; the latter asks Ribhu what boon he would like. Ribhu declines all worldly pleasures, and asks Vishnu to explain that science of Brahman which treats of thy nature, a knowledge which leads to salvation. From this point on, the Upanishad is structured as a sermon by Varaha to the sage Ribhu. It has five chapters with a total of 247 verses.