Patanjali was a Natha yogi in the same lineage as Jesus/ Isha Natha. Most scholars give the date of Patanjali as 200 BC, although some, quoted by Georg Feuerstein in the introduction to his translation of the yoga sutras of Patanjali, believe a later date of 250 AD is more likely. Patanjali’s guru was Nandinatha. For further details, please click on the page, Gurus of the Natha Lineage.
The Yoga Sutras of Patanjali comprise the seminal reference text on yoga. They are usually dated around 200 BC. Scholars such as Chandramouli S. Naikar suggest that Patanjail was not the author of the sutras but the redactor of an earlier oral tradition.
There are at least 50 translations of the text. Many of them can be found at http://hrih.net/patanjali/
Yoga is the quietening of the agitations of the mind.