The yoga science is one, even though there are many specialties within yoga (compare with medical science and its specialties).
Hatha yoga has become the most popular because most people identify with their physical body. But the body is really just the vehicle that allows the journey to the spiritual self to be undertaken. The practice of yoga is incomplete unless the subtler forces (mind, prana, etc) that impact on the body are understood.
The Hatha Yoga Pradipika states that 'The science of hatha is taught only for the sake of raja yoga. . . He who has climbed to raja yoga can deceive time and death.'
The word 'hatha' has different meanings at different levels. The grossest meaning is 'force', although in yoga it is gentle forcing of a new habit. At the next level, it means 'ha' =sun (active, masculine, right nostril breath) and 'tha' =moon (intuitive, feminine, left nostril breath).
In teaching yoga, one must start at the level of the pupil. Many people are aware at the physical level, but not the mental or spiritual levels. Only a few are aware of their posture. In yoga a primary consideration is the practice of mindfulness, self observation, being a witness to one's own body and its functions. This means not just the external surface, but also autonomic functions (skeleton, organs etc) and more subtle information that is in the mind (dreams). A yogi becomes aware of the state of the mind, how it is affected by the body, by stimuli, by foods. He becomes aware of the needs of the internal organs.
A student of hatha yoga thinks about the muscles, skeleton, nerves, breath and mind. Practice begins by visualisation in the mind, so that the mind trains the body (rather than vice versa). Only then practice physically, observe the mind commanding the muscles, observe the mind that is aware of the breath. Let it be an exercise in thinking, not doing. Then observe the visualisation in the mind, but without the physical practice. So develop hatha yoga as a thought process, watching the mind watching the body.
Three approaches to hatha yoga are discussed, tapas, worship and the evolution of mind.
Tapas or ascetic practice involves heating oneself up by exertion, not too much or too little (austerity). Practicing this way makes it a little easier, to the point where it becomes the norm. The mind says 'move' and the body moves.
Hatha yoga involves integration of mind and body, as in worship e.g. surya namaskara, sun salutation, thinking about the chakras and what the movements symbolise. The sun becomes symbolic of the object of workship. Think about the correspondence between the microcosm (the personality) and the macrocosm (the universe)-whatever is in the rough oval outline of the meditative body is also in the cosmic egg, and vice versa. Yoga establishes the connection betwen the two.
Life consists of cycles, creation, maintenance, dissolution. The same applies to the asanas. By extending maintenance, we extend time and the life span. In each posture there is an awareness of the mood evoked, an interpretation from the heart. Explore the connection between the posture, the mood, the thought, learn to control them. In a hatha yoga session, pass through the cycles of reincarnation, of being a tree, a locust, a cobra, a fish, create the mood you want.
Nothing happens in the body without first happening in the mind, this is where hatha yoga and meditation connect.
Hatha yoga philosophy teaches that whatever you dislike you should choose to do. Face what you are afraid of, find out what it is, and then it will run away from you instead of you running away from it.
A little physical discomfort, gladly taken, will prevent future longer discomforts e.g. keeping the body pure now will prevent longer-term illness. This is the first Niyama, cleanliness and purification (Shaucha). A mind with no occlusions (pure) is aware of its surroundings, aware of what is happening in the body, so the natural link between the pure mind and a pure body.
There are four links between hatha yoga and meditation:
The Yoga Sutras of Patanjali include three important aphorisms about postures.
Kundalini yoga is the yoga of energy currents, flowing through the channels in the spine: ida (left), pingala (right), sushumna (mainstream). The aim of kundalini yoga is to awaken the coiled-up energy lying in the lower centre of consciousness (base chakra) so that it can flow freely through all seven centres. Hatha yoga is a preparation for this awakening. The use of the bandhas (locks) assists the upward channeling of energy. Hatha yoga uses physical cleansing, whereas Kundalini yoga uses energy currents that are not visible, but they ultimately tap into universal energy.
The author presents eleven maxims based on the book. Hatha yoga is the path to Kundalini yoga. The energy channels in the physical body shape and are shaped by the subtle body. There is more in the subtle body than is apparent from the physical body.