1. Control by Abhyasa and Vairagya
Their (the mental modifications) control is done by practice and non-attachment.
Through Vairagya you will have to check the out-going Vishaya Vrittis and through Abhyasa you will have to cut the new spiritual path for the mind to move on. Vairagya serves the part of an anicut on the river of Vishaya Vrittis. It forms a strong embankment. It does not allow the Vishaya Vrittis to pass outside. Vairagya removes Pratibandhas or obstacles. Abhyasa gives Kaivalya Moksha. Without Vrittis one cannot enjoy sensual objects, (Vaishaya-Vyavahara). If the Vrittis along with Samskaras are destroyed, Manonasa or annihilation of the mind follows.
Here is the gloss of Vyasa: The stream of mind flows both ways; flows towards good and it flows towards evil. That which flows on to perfect independence, Kaivalya, down the plane of discriminative knowledge is named the stream of happiness. That which leads to rebirth and the flow down the plane of indiscrimination or ignorance, is the stream of sin. Among those, the flow towards objects is thinned by Vairagya or desirelessness; the flow of discrimination is rendered visible by habituating the mind to the experience of knowledge. Hence the suppression of the mental modification is dependent upon both.
2. What Is Abhyasa
Of these (Abhyasa and Vairagya), practice is the effort to secure steadiness of (the modifications of mind).
The effort to restrain all the Vrittis of the mind and to make the mind steady like the jet of a lamp in a windless place is Abhyasa. To drive back the mind to its source - Hridaya Guha, and get it absorbed in Atman is Abhyasa. To make the mind inward and to destroy all its out-going tendencies is Abhyasa. And this practice should be done for a long time without any break and with perfect devotion. This is mentioned in Sutra I-14.
In this Sutra Abhyasa is explained. As for Vairagya, refer to Sutra I-15.
3. Control by Suppression of Vrittis
The suppression of the modification of mind (the Nirodha Bhumi) is the junction with the moment of suppression, when the out-going impressions and impressions of suppression disappear and appear.
In other words, we can say that, by the suppression of the out-going Vrittis of mind and the development of modifications of control, the mind rests firm in Nirodha Bhumi. This is Nirodha Parinama (modification of control).
The mind remains in its real, unmodified state. It is very difficult to understand this and the following four Sutras. You must clearly understand the Chapter on 'Samadhi.' Vyutthana means the mind goes outward. Here it means Samprajnata Samadhi. When compared with Asamprajnata Samadhi, Samprajnata Samadhi is outward. Samprajnata Samadhi itself is a distraction of the mind. The passage from the Samprajnata to Asamprajnata Samadhi is very difficult and critical process. It is a trying stage. The Yogi must be very, very vigilant. If one out-going Vritti is checked and controlled, that powerful Vritti which checks the out-going Vritti is itself a modification. This also must be controlled. The mind should become absolutely waveless before Asamprajnata Samadhi is attained.
4. Make the Suppression Steady
Its undisturbed flow becomes steady by habit (continuous practice).
The controlling modifications (Nirodha Parinama) must arise so continuously as to become a regular habit. Habit will come only by continuous practice. Then alone Samadhi will come by itself.
5. Control Mind by Virtues
By cultivating the habits of friendliness (towards equals), mercy (towards inferiors), gladness (towards superiors), and indifference towards happiness, pain, virtues and vice, comes peace of mind.
The best and easy way of keeping the mind in a state of equanimity or evenness, which is conducive to the attainment of Samadhi, is described here. Maitri and Karuna will eradicate hatred. Mudita will remove jealousy. Mercy softens the hard heart and removes the cruel, harsh nature. By this practice, anger, Abhimana, hatred, egoism, envy of various sorts will vanish. Rajas and Tamas will be removed. The mind will be filled with Sattva. The fickleness of the mind will disappear. Ekagrata state of mind will come in. The mind becomes pure.
Samadhi cannot come in a mind that is filled with hatred, jealousy and anger. By the method of Pratipaksha Bhavana, any good virtue can be developed.
6. Control Mind by Pranayama
Or by exhalation and retention of breath.
In the previous Sutra it is stated that by developing virtues you can control the mind. Here, in this Sutra, another method of controlling the mind is given. All Vrittis will cease by the practice of Pranayama. Rajas and Tamas will be removed. The mind will become one-pointed. The body becomes light. The mind will become calm. Different exercises in Pranayama are given in Chapter VII of this book.
7. Control Mind by Vedantic Method
Cut off daily the branches of Sankalpa from the tree of Manas and ultimately destroy the tree of the mind at its root completely. The cutting off of the branches is only secondary. The eradication of the tree by the removal of ego is the primary thing. Therefore, through virtuous actions, if you destroy the idea 'I' which forms the very root of the mind, then it will not spring up again. The Brahma Jnana which enquires the true nature of 'I' is the fire which destroys the mind. It is the Jnanagni referred to in the Gita IV-37: The fire of wisdom reduces all actions (and the false 'I') to ashes.
He who knows the receptacle (Ayatana) verily becomes the receptacle of his people. Mind is verily the receptacle (of all our knowledge). (Chhandogya Upani- shad V-i-5)