The Paths of Yoga
According to the Bhagavad Gita there are four main Margas (paths) by which to reach the ultimate goal of Yoga - Kaivalya. There is the path of Knowledge (Jnana Marga) in which one learns to discriminate between what is real and what is illusory, the path of selfless work (Karma Marga), the path of devotion (Bhakti Marga) and the path of control of the mind (Yoga Marga) where all the activities of the mind and consciousness are studied and brought under control. From these have come the various paths of yoga which can be followed.
Raja Yoga involves mastery of the mind and senses in Samadhi; essentially the advanced aspects of Patanjali's Astanga Yoga.
Hatha Yoga is the yoga of the will which involves cultivating ones energy to arouse Kundalini primarily by means of Asana and Pranayama.
Mantra Yoga involves reciting sacred syllables to reach perfection.
Laya Yoga involves absorption in God to experience ultimate bliss.
Bhakti Yoga requires absolute devotion to God to achieve the ultimate goal.
Karma Yoga achieves this through selfless work without thought of personal reward.
Jnana Yoga is the Yoga of knowledge, cultivating the discrimination between spiritual reality and the illusion of the material world.
It must be realised that there are no clear cut boundaries between these various paths and all draw on the practices and philosophy of the others; effectively all paths have the same goal and "tread the same terrain." They are different views of the same topic.
The Schools of Yoga
Various schools or styles of Yoga have grown around each of these paths, which emphasise different aspects of these paths, or are a combination of them in their practical methodology. Usually these schools are established by renowned teachers or Gurus and reflect their methodologies and ways of practicing, teaching and following the path of Yoga. Some of the most well known modern schools or styles of Yoga include: Iyengar, Astanga, Vini, Ananda, Anusara, Sivananda, Kundalini, Integral, Kali Ray Tri, Kripalu, and Bikram. (See this article for a brief explanation of the differences between some of these schools at a practical level in terms of how classes are run). Interestingly, three of the most popular schools today - Iyengar, Astanga and Vini Yoga - were all developed by students of Sri T. Krishnamacharya.
Particular styles or methods may be considered more effective than others or may suit an individual's temperament better. That said, it must always be remembered that all these are merely different methods of reaching for the same ultimate goal. They are all aspects of the overall philosophy of Yoga.
The Philosophy of Yoga
The philosophy of Yoga comes from many sources and has been presented in many fashions with differing emphasis depending on the understanding of the author. The Vedas and Upanishads give some of the earliest references to the paths of Yoga. These scriptures form the basis of Indian religious practices but contain many varied references to Yoga and other things.
There are the ancient Puranas which deal with the nature of the universe. Famous epics such as the Ramayana and Mahabarata contain stories of the Gods and lectures on moral and philosophical subjects with references to yogis and yogic practices. The Bhaghavad Gita is a particularly famous part of the Mahabarata which contains a detailed discourse on Yoga by Krishna to Arjuna. Other texts such as the Hatha Yoga Pradipika are more "technical manuals" of Yoga which go into detail on technique as opposed to theory alone.
In general all these texts discuss Yoga from the particular standpoint of the authors and the paths to Yoga they have followed. In many ways this subject can be confusing for lack of a clear overview. This need is answered in the Yoga Sutras of Patanjali.
The Yoga Sutras of Patanjali
The various philosophies and methodologies of Yoga itself were clearly and methodically brought together and presented by the sage Patanjali in his set of 196 aphorisms called The Yoga Sutras, written some 2200 years ago. The Sutras bring together all the various strands of theory and practice from all sources of Yoga and present them in one concise, integrated and comprehensive text. How all the aspects interrelate and form part of the whole body of Yoga is clearly elucidated. There are 8 disciplines to Yoga as presented by Patanjali (thus Astanga Yoga - 8 Limbed Yoga) which must be practiced and refined in order to perceive the true self- the ultimate goal of Yoga:
Yama - Universal ethics: non-violence, truthfulness, non-stealing, sexual restraint and non-acquisitiveness.
Niyama - Principles of self conduct: purity, contentment, intense dedication or austerity, study of self and scriptures and self-surrender.
Asana - Practice of the postures.
Pranayama - Breath control.
Pratyahara - Withdrawal and control of the senses.
Dharana - Concentration.
Dhyana - Meditation.
Samadhi - A state of higher consciousness where the sense of self (ego) dissolves in the object of meditation and the individual self exists in its own pure nature.
Hatha Yoga - The Foundation Yoga of Vitality
Hatha Yoga is the foundation of all Yoga systems. Ha means "Sun" and Tha means "Moon". Thus, Hatha Yoga refers to positive (sun) and to negative (moon) currents in the body system. These currents are to be balanced and mastered so that vital force, Prana, can be regulated, the mind cleared and superconscious states experienced. With regular practice of asanas (postures) body cells are stimulated, blood circulation purified and the internal body cleansed. These asanas help to develop flexibility, increase energy and detoxify the whole body.
The ideal way to practice Hatha Yoga Asanas is to approach the practice session in a calm, meditative mood. Sit quietly for a few moments then begin the series slowly, with control and grace, being inwardly aware as the body performs the various postures.
Pranayama - Breath Control
Prana is the vital energy of your body. Pranayama is the measuring, control, and directing of the breath. It is a specific technique of breathing which aims to capture this vital energy and reach each cell of your body. It controls the energy within the organism, in order to restore and maintain health and to promote evolution. When the inflowing breath is neutralized or joined with the outflowing breath, then perfect relaxation and balance of bodily activities are realized. In Yoga, we are concerned with balancing the flows of vital forces, then directing them inward to the chakra system and upward to the crown chakra or Sahasrara (thousand petaled lotus).
Pranayama is very important in Yoga and goes hand in hand with the asana or pose. In The Yoga Sutras, the practices of pranayama and asana are considered to be the highest form of purification and self discipline for the mind and the body, respectively. The practices produce the actual physical sensation of heat, called tapas, or the inner fire of purification. It is taught that this heat is part of the process of purifying the nadis, or subtle nerve channels of the body. There are 72000 nadis in your body, each connected with the navel. This pranic breathing method clears any blocks in the nadis, cleanses the whole body system, organs and blood, and enables the subtle energy to flow throughout your body freely.