In Iyengar yoga, we often begin practice with the chanting of the Invocation to Patañjali. This sets the stage for a quiet and humble mindset which I find quite nice, especially in the company of fellow practitioners. Patañjali wrote the Yoga Sūtra, 196 aphorisms that describe the eight limbs of yoga.

The translation of the Invocation in Light on the Yoga Sūtras of Patañjali by BKS Iyengar is:  Let us bow before the noblest of sages, Patañjali, who gave yoga for serenity and sanctity of mind, grammar for clarity and purity of speech, and medicine for perfection of health.  Let us prostrate before Patañjali, an incarnation of Adiseśa, whose upper body has a human form, whose arms hold a conch and a disc, and who is crowned by a thousand-headed cobra.

Also told by B.K.S. Iyengar in Light on the Yoga Sūtras of Pataṅjali is the story of how he came to be.

It is said that once Lord Viṣṇu was seated on Ādiśeṣa, Lord of serpents, His couch, watching the enchanting dance of Lord Śiva. Lord Viṣṇu was so totally absorbed in the dance movements of Lord Śiva that His body began to vibrate to their rhythm. This vibration made Him heavier and heavier, causing Ādiśeṣa to feel so uncomfortable that he was gasping for breath and was on the point of collapse. The moment the dance came to an end, Lord Viṣṇu’s body became light again. Ādiśeṣa was amazed and asked his master the cause of these stupendous changes. The Lord explained that the grace, beauty, majesty and grandeur of Lord Śiva’s dance had created corresponding vibrations in His own body, making it heavy. Marveling at this, Ādiśeṣa professed a desire to learn to dance so as to exalt his Lord. Viṣṇu became thoughtful, and predicted that soon Lord Śiva would grace Ādiśeṣa to write a commentary on grammar, and that he would then also be able to devote himself to perfection in the art of dance. Ādiśeṣa was overjoyed by these words and looked forward to the descent of Lord Śiva’s grace.

Ādiśeṣa then began to meditate to ascertain who would be his mother on earth. In meditation, he had the vision of a yogini by the name of Goṇikā who was praying for a worthy son to whom she could impart her knowledge and wisdom. He at once realized that she would be a worthy mother for him, and awaited an auspicious moment to become her son.

Goṇikā, thinking that her earthly life was approaching its end, had not found a worthy son for whom she had been searching. Now, as a last resort, she looked to the Sun God, the living witness of God on earth and prayed to Him to fulfill her desire. She took a handful of water as a final oblation to Him, closed her eyes and meditated on the Sun. As she was about to offer the water, she opened her eyes and looked at her palms. To her surprise, she saw a tiny snake moving in her palms who soon took on a human form. This tiny male human prostrated to Goṇikā and asked her to accept him as her son. This she did and named him Patañjali.

Pata means falling or fallen and añjali is an oblation. Añjali also means “hands folded in prayer”. Goṇikā’s prayer with folded hands thus bears the name Patañjali. Patañjali, the incarnation of Ādiśeṣa, Lord Viṣṇu’s bearer, became not only the celebrated author of the Yoga Sūtras but also of treatises on āyurveda and grammar.