According to the Ayurvedavatarana (the "descent of Ayurveda"), the origin of Ayurveda is stated to be a divine revelation of the ancient Indian creator God Lord Brahma as he awoke to recreate the universe. This knowledge was passed directly to Daksha Prajapati in the form of shloka sung by Lord Brahma. and this was in turn passed down through a successive chain of deities to Lord Indra the protector of dharma. According to this account, the first human exponent of Ayurveda was Bharadvaja who learned it directly from Indra. Bharadvaja in turn taught Ayurveda to a group of assembled sages, who then passed down different aspects of this knowledge to their students. According to tradition, Ayurveda was first described in text form by Agnivesha in his book the Agnivesh tantra. The book was later redacted by Charaka, and became known as the Charaka Samhitā. Another early text of Ayurveda is the Sushruta Samhitā, which was compiled by Sushrut, the primary pupil of Dhanvantri, sometime around 1000 BC. Dhanvantri is known as the Father of Surgery, and in the Sushrut Samhita, the teachings and surgical techniques of Dhanvantri are compiled and complemented with additional findings and observations of Sushrut regarding topics ranging from obstetrics and orthopedics to ophthalmology. Sushrut Samhita together with Charaka Samhitā, served as the textual material within the ancient Universities of Takshashila and Nalanda. These texts are believed to have been written around the beginning of the Common Era and are based on a holistic approach rooted in the philosophy of the Vedas and Vedic culture. Holism is central to ayurvedic philosophy and elements of holism is found in several aspects of ayurveda.