The Sanskrit term for mind is Manas. Manas is said to be of two kinds, the pure and the impure. That which is associated with the thought of desire is the impure, while that which is without desire is the pure. The pure mind is otherwise known by the name higher mind. The impure mind is called lower mind. To men their mind alone is the cause of bondage or emancipation. That mind which is attracted by objects of sense tends to bondage, while that which is not attracted tends to emancipation. There is said to be salvation for a mind without a desire for sensual objects. An aspirant after emancipation should therefore render his mind ever free from all longing after material objects.
The impure mind or Ashuddha Manas is filled with impure Vasanas (tendencies in the mind), Rajas and Tamas and the pure mind or Shuddha Manas is filled with pure Vasanas and Sattva. The impure Vasanas generate rebirths. The pure mind with pure Vasanas leads to Moksha or liberation from births and deaths. The worldly-minded persons work with the lower or the impure mind. They are bound by their Karmas. The liberated sages work with the pure or Sattvic mind (higher mind). They are not bound by their Karmas as they have no egoism and as they do not expect fruits for their actions.
The impure mind is unsteady. It ever fluctuates. It jumps from one object to another. It ever hankers after sensual objects. It is filled with various sorts of fears and pains. The pure mind is steady. It does Brahma Vichara. It rests in Supreme Self. It does not move towards sensual objects. It is free from all sorts of fears and pains.
The impure mind is no other than the Vasanas (subtle desires) that generate countless births. The mind becomes a prey to various kinds of desires through its fluctuation. Fluctuation is caused by Rajas and Vikshepa Shakti. When the mind fluctuates, it wanders from one object to another object.
The Ajnani or worldly minded man is swayed by the impure mind. He acts according to the dictates of the lower or impure mind. But a sage or Jnani keeps his mind under his perfect control. He acts in accordance with the voice of his intuition.
Just as a washerman removes dirt through dirt, just as a traveller removes the thorn in his foot through another thorn, so also the impure mind should be slain by the pure mind.
He who has annihilated the lower or the impure mind drives away rebirths to a great distance from him. The pure Vasanas with which the sage performs actions cannot produce rebirths for him.
All impure Vasanas are fried in toto when you get knowledge of the Self or Brahma Jnana. Meditation, Japa, Kirtan, practice of Pranayama, Brahma Vichara, study of religious books and Satsanga generate pure Vasanas.
When the mind is freed from the desires for objects and when it rests in the Self or Atman, you will enjoy Eternal Bliss. When the mind is freed from all cravings or longing for objects, when it is controlled in the heart, when it attains the reality of the Atman, you will attain Moksha or the final beatitude of life.
O beloved Ram! Do not allow your mind to fluctuate. Render your mind ever free from all longings after material objects. Annihilate the impure or lower mind with the help of the pure or the higher mind and transcend the higher mind also. May you be as firm as a rock! May you be endowed with the pure or Sattvic mind! May you ever rest peacefully in the All-blissful Self!
Message from the book Lectures on Yoga and Vedanta.