“There are six classical schools of Indian philosophy. In Sanskrit these are called the “Shad Darshanas” meaning “six philosophies.” The term "darshan" means "to see." Philosophy is the conclusions of the rishis who are able to "see" the truth and then convey it to others. The six schools of philosophy are "astika" which is commonly translated as "orthodox, traditional or theistic." There are several "nastika" schools, meaning "non-traditional, heterodox or atheistic." The two main nastika schools are Buddhism and Jainism. The six astika schools accept the Vedas as the final authority. The nastika schools trace their roots to the Vedas but are more interpretive and openly question some tenets. Some say that the astika schools are theistic (God exists) and the nastika schools are "atheistic" (God does not exist). But, exploration of these philosophies reveals that this division is not so easy to make as definitions of God vary. The student may wonder about where Hinduism fits in. What is called Hinduism is various interpretations of knowledge from the six astika schools of thought. Hinduism is more of an umbrella than a singular teaching and there are many variations.
Ayurveda draws its knowledge from all six astika schools of thought. The six schools of Indian philosophy are Sankhya, Nyaya, Vaisheshika, Yoga, Mimamsa, and Vedanta. All of these philosophies have their origins in the Vedas. Sankhya philosophy is considered the predominant philosophy in Ayurveda as regards creation. It is also the principal philosophy that is behind the cosmic view taken by Yoga. For this reason, Sankhya and Yoga are often combined in discussion and writings as Sankhya-Yoga.”
Excerpt from “Principles of Ayurvedic Medicine,” by Dr. Marc Halpern, Founder of the California College of Ayurveda