Patanjali 
Yoga Sutras of Patanjali [EPUB ebook] 

This book provides a complete manual for the study and practice of Raja Yoga, the path of concentration and meditation. The sutras begin with the most basic concentration, and then progresses to discipline, manifestation, and finally, emancipation of the transcendental ego. It is now considered one of the most important textual sources for the practice of yoga. This classic work of Indian philosophy spells out succinctly how the mind works, and how it is possible to use the mind to attain liberation.