The mind is not a linear entity. It has deeper layers which ordinarily we are unaware of. The mind can be likened to an iceberg. One can see only the tip of an iceberg, the majority of which lies submerged below stretching way down to the bottom of the ocean. In the analogy of an iceberg, which is pyramidal in shape, the tip of the iceberg represents your conscious mind, the vast base of the iceberg represents the unconscious mind and the middle portion represents the sub-conscious mind. Ordinarily one is aware just of the tip of the iceberg (the conscious mind) with no inkling of the sub-conscious or unconscious layers.

All your interactions with the external world – perceptions, learning, thinking – basically all cognitive processes occur through your conscious mind. The conscious mind is the medium of learning, knowing, acquiring new skills. The sub-conscious mind, on the other hand, is like a sponge that absorbs all sensory information present in the environment. Some of this information trickles down through the conscious mind but a major chunk of sensory perceptions are directly stored in the sub-conscious mind.

Now, it is simply inconceivable to assess the vast amount of information present in the sub-conscious stratum. All your conscious experiences and learning get stored in the sub-conscious mind. For example, once a child has learnt his alphabets, he doesn’t have to re-learn them, for the information is well stored in the sub-conscious layer. And thus, as you grow, so does this storehouse of information which is extracted by the conscious mind, whenever needed.

But there are times when although this information is present in the deeper layers of the mind, nevertheless you are unable to recollect it. For example: If I ask you, in which year did Columbus discover America or in which year did emperor Shahjahan ascend to his throne? Most of you would have read this as part of your school curriculum, so the information is there, but not all of you will be able to retrieve it. The information which is not needed in your day to day life, that stuff ends up being stored in the sub-conscious mind. On the contrary, the stuff we relate to everyday like the registration number of your car, your telephone number, your address and so on, all these are part of your active memory and can be retrieved easily.

In contrast to this, it will be difficult to recollect the name of the person who used to sit behind you, say when you were in fourth standard, because this kind of information is not needed in your day to day life. It is easier to recollect such things or events which you have to relate to every now and then. But importantly, you can recollect only that, you can reminisce over only that which you have perceived in the past. After all, can your mind think about something you have never heard, never seen, never smelt, never tasted or never touched?

As far as the unconscious mind is concerned, for now understand that it represents deep, vast darkness. It is like a dormant seed that holds countless experiences of pain and pleasure, emotional upheavals, thoughts, viparya (wrong knowledge) from all your previous lifetimes. The unconscious mind shapes up your sub-conscious mind, and your sub-conscious mind in turn shapes your conscious mind. In yogic language, the sub-conscious and unconscious mind is collectively referred to as chitta. And Patanjali’s yoga sutra (precept) clearly states: yogaś-citta-vrittinirodhah, which means ‘yoga is the total cessation of all tendencies, all modifications, and all fluctuations of the chitta.’ Patanjali’s yoga sutras commences with this very aphorism. And note that he is talking about cessation of all modifications of the sub-conscious and unconscious mind – ending of all desires, all vāsanās, all viparya, all thoughts, all counter-thoughts. The mind thus is in a state of absolute stillness.

The seeds of vāsanās (force of desire, innate tendencies) lie in the deeper layers of the mind. And whenever a seed sprouts, it affects the sub-conscious mind first which then propels the conscious mind to acquire the desired object whether it is to eat something, go somewhere, buy something, indulge in sex, or indeed anything else. Whatsoever is the desire, know that it is being pushed from the sub-conscious to the conscious mind. As long as you haven’t cleansed the dirt of vāsanās lying in the sub-conscious mind, they will keep on awakening and keep popping as desires in the conscious mind. So, how can you access your sub-conscious mind, you may ask? This is through the method of pratyāhāra called yoga nidra. Yoga nidra is the method wherein you can, not only access but cleanse all your deep lying samskārās and vāsanās. Furthermore, yoga nidra can give you the experience of being separate from the body, which won’t otherwise be achieved by blindly repeating ‘I am not the body’ even if you keep reciting this till the cows come home!

But yoga nidra can give you this experience very soon, as some seekers are already experiencing. But those who are yet to experience this through yoga nidra needn’t worry, just keep practicing patiently. You can access your sub-conscious and even unconscious mind through yoga nidra. And then it is up to you – what memories, desires, samskārās you want to keep and what you want to eliminate, this choice is given to you by yoga nidra. In my experience and in my opinion, yoga nidra is a very powerful tool for modern man.

Remember, all that you perceive through your senses in your waking state, be it knowingly or unknowingly, all of those impressions are left in the deeper layers of your mind in the form of samskārās. And it is these trillions of samskārās that keep on giving rise to specific thoughts and emotions in your mind. That is why a spiritual aspirant needs to be constantly alert – aware at all times of every thought, every emotion arising in his mind. For even a moment’s lapse of awareness will ripen the thought or emotion, and consequentially you will end up performing such actions which you later end up regretting. You don’t want to do something, yet it just happens because of the force of the awakened samskārā.

There are only two ways of eradicating these samskārās: Vairāgya (dispassion to the objective world) is one way, and the other is sincere practice of pratyāhāra (withdrawal of the senses from the objective world) and dhyāna (meditation). When the mind is integrated, and the senses are withdrawn from the external world of phenomenon (pratyāhāra), then the next stage i.e. dhāranā takes place. And it is only when dhāranā ripens that you will get to understand the mind in totality (conscious, sub-conscious and unconscious).