Patanjali & Charles Johnston 
Yoga Sutras of Patanjali [EPUB ebook] 
The Book of the Spiritual Man

The Yoga Sutras of Patanjali discuss the philosophy on which yogic practice is based. It is an ancient and enormously influential piece of work, still relevant today. The Sanskrit word "yoga" describes the suspension of thoughts and feelings experienced during practice, and "sutra" is a thread on which beads – or in this case aphorisms – are strung. The work is sometimes referred to in English as The Yoga Aphorisms.