The concept of Triad (or Trimurti, Trinity) makes a relatively late appearance in Hindu literature, or in the second half of 1st millennium BC. The idea of triad, playing three roles in the cosmic affairs, is typically associated with Brahma, Vishnu and Shiva (also called Mahesh); however, this is not the only triad in Hindu literature. Other triads include Tridevi, of three goddesses - Lakshmi, Saraswati and Parvati in the text Devi Mahatmya, in the Shakta tradition, who further assert that Devi is the Brahman (Ultimate Reality) and it is her energy that empowers Brahma, Vishnu and Shiva. The other triads, formulated as deities in ancient Indian literature, include Sun (creator), Air (sustainer) and Fire (destroyer); Prana (creator), Food (sustainer) and Time (destroyer). These triads, states Jan Gonda, are in some mythologies grouped together without forming a Trinity, and in other times represented as equal, a unity and manifestations of one Brahman. In the Puranas, for example, this idea of threefold hypostatization is expressed as follows,