The mind stuff is citta. It is a mental substance. Vrtti or thought-wave is a modification of the mind-stuff. It is a process. Just as waves and bubbles arise from the surface of the ocean. so also these vrttis arise on the surface of the mind-ocean. Just as the sun’s rays emanate from the sun, so also these mental rays (modifications of the vrtti), emanate from the mind-sun. Just as the sun merges itself into the horizon at sunset, by collecting all its rays, so also you have to merge in the sun of suns, absolute consciousness, eternal peace, by collecting all the dissipated mental rays and dissolving the mind itself.
The function of the vrtti in the mind is to cause the removal of the cause of ignorance covering objects. Gross ignorance is enveloping all objects. When it is removed, then perception of objects becomes possible.
Through its own effort the mind assumes the shape of any object, and concentrates upon itself. When the mind thinks of Brahman, the sole ultimate thought of Brahman is formed. Be vigilant. Watch the mind and its activities. The object does not bind you – it is the vrtti, the identification with the vrtti, that causes attachment and bondage.
If you become one with the mind, body and vrttis you get various sorts of miseries and sufferings. The whole universe is created by the vrttis alone. If these mental thought-waves subside you can attain the absolute state of highest peace and bliss. Just as soap cleanses the physical body, even so japa (repetition) of any mantra, dhyana (meditation) and klrtan (chanting), together with the practice of yama and niyama (discipline), cleanse the mind of all impurities. Just as you nourish the physical body with food, even so you will have to give food for the mind and spiritual food for the soul.
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Only when the modifications cease do you enter the silence. Realise this. Close the eyes, draw in the senses, still the mind, silence the thoughts, sharpen the intellect, purify the citta, meditate on Om and chant it with feeling. Enter the silence. Silence is atman, the centre – it is in the heart-cave. When the mind runs from one object to another, the state in the interval, wherein you become mindless, is Brahman.