The Yoga Sutras of Patañjali
The following excerpt from “Enlightenment!” is an excellent description of the Yoga Sutras of Patañjali:
“Sutras are very short and concise statements. Sutra literally means “thread.” The Yoga Sutras are the threads that together constitute the tapestry of Yoga. Yoga comes from the root, yug, which means to join together. So the Yoga Sutras are the threads that join together. Yoga is the science of joining together the individual lower self with the universal higher Self, the indivisible spark of God that resides within everyone. Yoga is not a belief system or a religion nor even a philosophy--it is an extremely practical methodology for systematically expanding the conscious mind. Said another way, Yoga is the Science for overcoming the self-destructive and limiting beliefs and internal programs that keep individual life bound to the experiences of the Waking State of Consciousness--the state in which life is alternately happy and sad, loving and hating, healthy and sick--in short, dual. Yoga provides a systematic ladder for climbing beyond the often painful experiences of the Waking State of duality into the state of non-changing Unified Consciousness, a.k.a. full enlightenment.”
Here is a PDF (1MB) file with the entire text of Yoga Sutras written in devanagari script with Sanskrit transliteration. This is a useful information resource that can be downloaded and printed for your studies of the Yoga Sutras. Sometimes it is useful to have the raw Sanskrit without the translation for study purposes.