Patanjali, the ancient sage, articulated the classical system of yoga perhaps more succinctly than anyone. Born before 400 B.C., Patanjali compiled a set of roughly two hundred aphorisms that explained the entire process of yoga from start to finish.
These aphorisms have influenced and inspired generation after generation of genuine seekers, each one of whom must eventually has to grapple with the terse sincerity of these statements.
The Yoga Sutras describe most importantly the process of yoga found within the school of Raja yoga. For a description of the other three traditional schools of yoga — karma yoga, bakti yoga, and jnana yoga — visit my article on them here.
The Yoga Sutras outline the process of yoga as a gradual process of refinement of the body and mind. Patanjali enumerates the process of Yoga into eight steps, often referred to as limbs, which are the following:
Yamas refer to the things that you shouldn't do. Don’t harm, don’t lie, don’t steal, and don’t covet, and don't overly indulge. You can think of these as a sort of set of commandments, like the 10 commandments, except that they are not a set of orders from an authoritarian personified supernatural god, but rather a set of common sense codes that will ensure good karma and general health and happiness.
Niyamas refer to the things that you should do. Do maintain study, purity, contentment, and discipline. And do practice surrender. Niyamas, along with yamas, are a way to purify your actions. Doing these things will ensure a strong foundation for your life.
Asanas refer to the activities of Hatha yoga, the physical exercises, the movements and postures that most people mistake as encompassing the entire system of yoga. So to avoid confusion throughout your everyday life, you could easily substitute the word asana almost every time you encounter the word yoga applied to a class, studio, teacher, or magazine.
The asanas are a way to purify the body. If you live in a body that is unhealthy and impure, you will not possess adequate preparation to study the breath and the mind. Asanas are easy to perform, and all you have to do is visit your local yoga studio (ahem ... asana studio!) and an instructor will guide you through them.
Pranayama refers to the breathing practices. The breath is the bridge between the body and the mind. You can manipulate the breath in order to calm the body and mind as preparation for meditation through a variety of techniques. These techniques include mainly deep breathing or fast breathing.
Pranayama, along with asanas, niyamas, and yamas are in many ways a prerequisite for the more complex and challenging steps within the practices of meditation. These steps are explained within the next four limbs.
Pratyahara refers to the control of the senses and detachment from the distractions of the external world. By closing your eyes and focusing your attention inward, you remains unaffected by stimulus from the surrounding environment.
Dharana refers to the steadying of the mind onto a single object of focus. By choosing a single object of focus, you begin to undercut the subject object dualism, which paves the way to deeper meditation. Dharana is synonymous with concentration.
Dhyana refers to absorption into the object of focus. You become one with the object, totally identified with it and only it. Technically speaking, meditation has not actually begun until you have achieved dhyana.
Samadhi refers to the supreme state of meditation, total transcendence of the object of focus, the state of bliss which defies description.
While samadhi is listed as the last of the eight limbs of yoga, Samadhi is a trance state and thus only an intermediate goal on the path to "full" enlightenment. "Full" enlightenment — and I emphasize that with quotations because enlightenment is actually a never-ending process, as we are constantly in the process of expanding our awareness throughout the entire universe — requires the integration of these advanced states of meditation into daily activities.