What is the difference between control and suppression ? How do we know if desires have to be exhausted, suppressed or controlled ?
There is a big difference between control and suppression in spiritual philosophy. I am using the term "spiritual philosophy" and not just Yoga, Tantra, Vedanta or Samkhya; all philosophies are included. The difference is that in suppression you are not aware of the reactions that may be taking place or that will take place later on, but in control you are. The key factor is awareness. Lack of awareness is suppression and having awareness is control.
Let us take food as an example. Suppose that, after having spent one year in the ashram eating dry chappati, rice, dal etc., you go out and see a nice, sumptuous meal. What do you do? You gorge yourself! The desire for such food has been there all the time, but it has been suppressed in the ashram. So you fill yourself, and after bloating the stomach you cry, "Oh, I feel so heavy, I feel sick, what should I do?"
However, when you have control you eat with restraint according to the capacity of your stomach, being aware of the desire, which has been suppressed while you were in the ashram. If you are able to control it, then that desire governed by awareness does not create a problem. The desire has been there all the time; it has been building up all the while. In the first instance, it overcame you, but in the second you were aware and you let it go in a controlled way.

Awareness makes all the difference between suppression and control. Desires arc always for some kind of self-satisfaction. Even when we desire our own development it is selfish. If we desire to help others it is still selfish. To desire realisation is also selfish. Desires can never be neutral or transcendental. Our prayers to God are similarly selfish. Only the object of desire has changed from money to realisation, from wealth and prosperity to serving others. The attitude has changed but the desire is still there and desire is selfish.
The changing of our attitude and perception is necessary, but this can only happen when we are not sunk in ignorance. The realisation must come that we need to change our attitude. Instead of doing something for our fulfillment, we need to do something to help others. It is the attitude of the ego which has to change.
The first step in this effort to understand the mental processes is self-analysis through the techniques of pratyahara, dharana and dhyana. Once we are able to understand what kind of thoughts, emotions, desires and experiences take place within us, we can slowly change our attitudes. Then suppression will become control. Once you have that control you will also gain the ability to allow everything that is bottled up (emotions, feelings, ambitions, desires and so forth) to come out in a systematic and controlled way.
From the book “On the Wings of the Swan, Vol.1”, pg.113-114, Sw. Niranjanananda Saraswati






