The eight fundamentals or accessories of Raja Yoga, as it has been described by Maharshi Patanjali, are Yama, Niyama, Asana, Pranayama, Pratyahara, Dharana, Dhyana and Samadhi. These eight accessories are like the eight rungs in the ladder of Raja Yoga. They all should be practised in the order given. Through the practice of these eight accessories, the impurities of the mind are destroyed and the light of wisdom, the discriminative knowledge illumines the life of the practitioner. Then he attains Kaivalya or the Supreme Perfection.
Now, Yama is the practice of Ahimsa (abstinence from injury or non-violence), Satya (truthfulness), Brahmacharya (continence), Asteya (abstinence from theft or earning through illegal methods) and Aparigraha (abstinence from avariciousness or greed).
The other restraints that follow have their origin in Ahimsa. Practice of Ahimsa culminates eventually in realisation of unity or oneness of life, of cosmic love and universal brotherhood and ultimately the Advaitic consciousness. The second aspect of Yama, viz., Satyam or truthfulness is the most important qualification of a Sadhaka. Truth is the symbol of God and He can be realised only through unflinching adherence to truth. The fourth aspect i.e., Asteya means complete annihilation of one's pilfering nature. The Sadhaka has to be contented with whatever he gets through honest means. He must completely abstain himself from illegal appropriation or confistication of others' property and other illegal ways of maintaining his livelihood. Brahmacharya, the third aspect, means purity in thought, word and deed. No Yoga or spiritual evolution is possible without the observance of rigid celibacy. The fifth and the last aspect of Yama i.e., Aparigraha means freedom from greed or covetousness. The aspirant should live on the barest necessities of life, abstaining from receiving any gift or presentation from others. He must live independently without the support of others.
The second accessory of Raja Yoga viz., Niyama is the observance of the five canons: Saucha (internal and external cleanliness), Santosha (contentment), Tapas (austerity or mortification), Svadhyaya (study of scriptures) and Isvarapranidhana (worship of God or self-surrender).
The first aspect of Niyama, Saucha or purification is of two kinds: internal (mental) and external (physical). Cleanliness is next to godliness. Just as you need soap, water etc., for washing the body, so also you need Japa, Kirtan, prayer, meditation and selfless service for washing your mind. Keep the body always neat and clean and the mind always pure and healthy, free from evil thoughts, evil desires or cravings. The second aspect Santosha or contentment brings a fullness of life, happiness and peace. If there is no contentment, the mind is always restless and ruffled, and naturally the Sadhana becomes impossible. The third aspect-Tapas is austerity of the mind and the body. You should be able to bear heat and cold, physical discomfort and fatigue, as well as insult, injury, persecution and any sort of humiliation or crucifixion. You should keep your body and the senses ever pure and carefully guarded. The fourth aspect-Svadhyaya or the study of scriptures and religious books, elevates and inspires the mind. It gives you an idea of your goal and the necessary practices that are necessary for its accomplishment. Practical application of what you read that are amicable to your temperament and applicable to your mode of life, is very necessary if you wish to derive any permanent, substantial benefit out of your study. The fifth and the last aspect of Niyama-Isvarapranidhana is worship of God and ultimate self-surrender. Worship Him with a pure heart and stainless mind, surrender your ego at His feet, and annihilate the idea of doership or separateness from the Lord. You will realise the Advaitic Oneness of the Self.
Asana is the third Anga of Raja Yoga. Physical fitness, a diseaseless healthy body is essential for spiritual practices. Without good health you cannot fight against the turbulent senses and the boisterous mind. Regular practice of Asanas will keep the body fit and the mind calm, and will give you abundant energy, vigour, strength and nerve-power. You will be able to do intense Sadhana without physical discomfort.
Padmasana, Siddhasana and Sukhasana are prescribed for meditation. For all-round physical and internal development, Sirshasana, Sarvangasana, Matsyasana, Paschimottanasana, Ardha-Matsyendrasana, Bhujangasana, Dhanurasana, Salabhasana, Trikonasana, Padahastasana, Halasana and Mayurasana are the important ones. Bandhas and Mudras are auxiliaries to Asanas.
The fourth Anga or accessory-Pranayama is regulation and control of breath. Literally it means the process by which you can know the secret of Prana and its control. The mind can be made to transcend ordinary experience and exist on a plane higher than that of reason known as superconscious state of concentration and also beyond the limit of concentration. The Yogi comes face to face with facts which ordinary consciousness cannot comprehend. This is achieved by proper training and manipulation of the subtle forces of the body so as to cause them to give, as it were, an upward push to the mind into the higher planes. When the mind is so raised into the superconscious state of perception, it begins to act from there and experiences higher facts and higher knowledge. Such is the ultimate object of Pranayama which is achieved through the control of the vibratory Prana.
That which moves through the nerves of the physical body is gross Prana. That which moves in subtle tubes of Yoga Nadis of the astral body is subtle Prana or psychic Prana. Breath is an external effect or manifestation of the gross Prana. There is intimate connection with the gross Prana and the subtle Prana. The control of the external breath leads to the control of the gross and subtle Prana of the body and mind. Hence Pranayama-exercises are practised. When the Prana and the mind are controlled, then all the mental modifications cease to arise. Then you become the master of your mind and body. Then dawn the intuitive knowledge of the Self, and you realise your essential nature-the supreme Reality.
The important Pranayamas practised are: Sukha Purvaka (Puraka, Kumbhaka and Rechaka), Bhastrika, Ujjai, Sitali, Sitkari, Kapala Bhati, Plavani, Brahmananda Murcha and Surya Bheda.
Now about the fifth accessory-Pratyahara is abstraction. It is the withdrawal of the senses from the objects. The senses are assimilated in the mind which is rendered pure through the practice of Yama, Niyama, Asana and Pranayama. The mind becomes more calm now. The nature of the senses is to have always connection with the objects. Where the vision is turned outward, the rush of fleeting events engages the mind. The outgoing energies of the mind begin to play. When they are obstructed by the practice of Pratyahara, the other course for them is to mix with the mind, to be absorbed in the mind. The mind will not assume any form of any object. It will be ultimately merged in the Self within.
Pratyahara itself is termed as Yoga, as it is the most important Anga in Yoga Sadhana. The first four rungs deal with ethical training and purification of the body, mind and Nadis. Now with Pratyahara proper Yoga begins, which eventually culminates in Dharana, Dhyana and finally in Samadhi.
Dharana or concentration is fixing the mind on something, internal or external. Having controlled the Prana through Pranayama and the senses through Pratyahara, you should now try to fix your mind on the Self within. The beginners should practise Dharana or concentration on some external object or on the form of their tutelary Deity. Thus when the mind gets trained, turn the gaze inward and it will naturally merge in the Self within.
Concentration is practised on the tip of the nose, or on the Ajna-Chakra (the space between the two eyebrows), or on Sahasrara (particularly for those who are inclined to Jnana Yoga Sadhana), or on the Anahata Chakra (for those who are of devotional temperament) or upon any of the six Chakras. Concentration is also practised externally on the idol or picture of the Lord or upon any particular spot or mark.
Prolonged Dharana is termed as meditation. It is a continuous, unhampered flow of one thought of God or the Self. Meditation is of two kinds, viz., Saguna and Nirguna. In Saguna or concrete meditation, the student of Yoga meditates on the form of his tutelary Deity; and in Nirguna or abstract meditation he meditates on his own Self or Atma. Nirguna meditation follows Saguna meditation.
The same Dhyana is Samadhi when it shines with object alone, as it were, devoid of itself. The thinker and the thought, the meditator and the meditated become one. The mind assumes Divya-rupa. The separate notions, contemplation, contemplated and contemplator vanish. In the state of Samadhi the aspirant is not conscious of any external or internal objects. With the destruction of the wandering mind, and with the increase of the one-pointed nature of the mind, the mind assumes the state of Samadhi. The bliss that is derived from that state of superconsciousness is inexpressible. It is beyond words. It is beyond apprehension of the finite mind. You will have to experience this by yourself only. There are different stages of Samadhi which ultimately lead to Nirvikalpa Samadhi. Here all Sadhana ends, and the Yogi becomes one with the Immortal Lord, one with the cosmic spirit. He is immanent and yet transcendent.