The Yoga Sutras of Patanjali are one of the six darshanas of Hindu or Vedic schools and, alongside Bhagavad Gita and Gherand Samhita, are a milestone in the history of Yoga. Yoga Sutras are a set of aphorisms (sutras), which are short and easy to memorize. They are part of an ancient oral tradition, which means you do not learn by reading and reasoning alone but you listen and chant. Though brief, the Yoga Sutras are an enormously influential work that is just as relevant for yoga philosophy and practice today as it was when it was written.
The title of the Patanjali's work consists of two Sanskrit words: Yoga and Sutra. 'Yoga', as used by Patanjali, refers to a state of mind wherein thoughts and feelings are held in check, and 'Sutra' means thread. It refers to the thread of a mala, upon which the yoga aphorisms are strung like beads. For that reason, the title is sometimes rendered in English as the 'Yoga Aphorisms'.
Yoga as a system of thought and practice has a primary reference to the philosophical system that flows from the teachings of the ancient Indian Yoga philosopher, Patanjali. Other great works elaborating on Yoga are the Siva Samhita, the Hath yoga Pradipika and the Gherand Samhita. Shiv Samhita is the fundamental work on yoga, said to originate from Lord Shiv, the founder of yoga. The Gherand Samhita is much more practical. It comprises of seven lessons covering aspects such as asanas (32 of them to be specific), how to perform it and its effects; mudras (25 of them), the control of senses, pranayam (breath control), meditation, and super consciousness. The Hatha Yoga Pradeepika by Swami Swatmarama is a much later text (16th Century) which deals with the pre-requisites of yoga, the asanas, pranayam, mudras, bandhas and Raj Yoga.
The Patanjali's Yog Sutra provide terse treatment to the complex subject of Yoga and seamlessly covers aspects such as types of yoga, practice of yoga, powers of yoga and the ultimate aim or result of yoga. Yoga Sutra deals with the subject matter at a psychological, psychosomatic and metaphysical level. Although a spiritual document, Yoga Sutra does not deal with specific Gods, chakras, kundalini or other trappings of the varied yogic traditions. It does not even elaborate us on how to perform any postures. In all, Yoga Sutra comprises of 195 aphorisms divided into 4 chapters or Pada, as follows:
1) Samadhi Pada (51 sutras)
2) Sadhan Pada (55 sutras)
3) Vibhuti Pada (55 sutras)
4) Kaivalya Pada (34 sutras)
In spite of the Yoga Sutra being by far the most definitive text on
the philosophy of classical yoga, very little is known about its author, Patanjali himself. In fact, the identity of this sage scholar is still being debated in academic circles. Maharshi Patanjali is believed to have compiled his Yoga Sutra around the 3rd or 4th century BC but archeological evidences and the study of ancient scriptures suggest that yoga was practiced in ancient India as early as 3000 BC.