One of the main schools of orthodox Hindu philosophy. It seeks “union” with the Absolute via a practical system of philosophically grounded sadhana (spiritual practices). It is the philosophy expressed by Patanjali in the Yoga Sutras, an ancient dualistic yogic approach that distinguishes between purusha (Spirit) and prakriti (Nature). The text is the first systematic exposition of yoga and explains the fundamentals of yogic philosophy. The term Classical Yoga also denotes the important period in the history of yoga when the Yoga Sutras was very influential (around 200-600 A.D.). After this period, Tantric influences became more prominent in India. Read more.