States of Mind and Concentration
Ramana Maharishi said "Concentration is not thinking of one thing. On contrary, it is excluding all thoughts obstructs the sense of one's true being. All efforts are to be directed simply to removing the veil of ignorance."
According to Patanjali yoga, the habitual state of mind is classified as five distinct states as follows,
1. Restless: This is the common state of mind where one’s mind get totally bombarded with thoughts, worries, etc. This phenomenon is a naturally unsettled state of the mind in the ordinary people. In this state, the concentration of the mind becomes pretty difficult. The mind cannot contemplate on the subtle principle which goes beyond the limit of the mental condition of that person.
2. Stupefied: This state of mind connects with the sensual perceptions. The mind is in a state of confusion and obsession. The mind gets filled with the desires and unnecessary thoughts. When one concentrates in this state of mind, his thoughts are mainly concerned with the wealth and prosperity. His mind will get occupied with the thoughts of his family, surrounding and day to day life matters. This state of mind is unfit for concentrating on the subtle principles.
3. Distracted: This is the state of mind which get partially filled with the distractions. This distracted mind interferes with two states as one is calmness and the other is restless. This state can be readily seen in the persons who were recently stepped to spiritual practices. In this state of mind, the aspirant can understand the nature of subtle principle and can also contemplate on them. The concentration of mind is even possible for the distracted state of mind. But it is only temporary and does not last for an extended period because the mind will be calm in one time and restless in another. (Also, see Psychology of Kundalini Meditation)
4. One-pointed: The potential of the mind becomes apparent in this state. The mind becomes one-pointed and contemplates on a single aspect. This state also has the directional nature and becomes more controllable. The one pointed in the sense means having a mere single thought or aspect which does not give rise to any following successive thoughts. It is that one thought is repeated over and over again in succession. Hence, this state of mind is defined as the one-pointed mind. When the aspirant gets mastered in this state, he can even induce the one pointed thought also in his dream. He will have complete control over the mind, and he will be able to resist and block the unconscious sinful thoughts that are arising in his mind. (See Siddhis or Mystical Powers)
5. Arrested: The above state is that which is having only a single successive thought in mind. Whereas in this state that a progressive thought of the mind gets arrested. Hence, the mind experiences the complete stillness, and it is the ultimate condition of the mind. One who attained this state can completely shut down all the thoughts for a longer period. This state is the one where the mind stops its function and thus leading to salvation. It is the only state where the liberation is possible even though concentration is possible in the above two states.
The book “Why Kundalini Meditation So Special?” gives a clear understanding of such practices and more over a guide for those who seek the path in this field.