The presiding deity of the Guruvayur Temple is Vishnu, worshipped in the form of his avatar Krishna. The central icon is a four-armed standing Vishnu carrying the conch Panchajanya, the discus Sudarshana Chakra, the mace Kaumodaki, and a lotus with a Holy basil garland. This image represents the majestic form of Vishnu as revealed to Krishna's parents Vasudeva and Devaki around the time of Krishna's birth. Worship proceeds according to routines laid down by Adi Shankara and later written formally in the Tantric way, the inter-religious spiritual movement that arose in medieval India, by Chennas Narayanan Nambudiri (born in 1427). The Chennas Nambudiris are the hereditary tantris (high priest) of the Guruvayur Temple.