The theory and practice of Yoga, in different styles, has been a part of all major traditions of Hinduism, and Shiva has been the patron or spokesperson in numerous Hindu Yoga texts. These contain the philosophy and techniques for Yoga. These ideas are estimated to be from or after the late centuries of the 1st millennium CE, and have survived as Yoga texts such as the "Isvara Gita" (literally, 'Shiva's song'), which Andrew Nicholson – a professor of Hinduism and Indian Intellectual History – states have had "a profound and lasting influence on the development of Hinduism".