Ramanuja, a Brahman who taught in the great temple of Srirangam, is said to have lived from 1017 to 1137, but the first date is in all probability several decades too early. Like Sankara, he taught in many parts of India, and claimed to base his doctrines on earlier sources, writing lengthy commentaries on the Brahma Sutras, the Bhagavad Gita and the Upanishads. Ramanuja's system was founded on that of the Pancharatras, but his emphasis was rather different. He admitted the usefulness of ritual observance, but only in a qualified measure, and he also admitted Sankara's doctrine of salvation by knowledge, but declared that those so saved would find a state of bliss inferior to the highest.