The power of concentration is the means by which to acquire not only the power of telepathy, but will-power, moral power, inspirational power, moral courage, mental strength, physical strength, and so for all the different kinds of development in life it is the first stage, and maybe it is the last stage, when the person's eyes open to real light.

There are three different steps in concentration: observation, concentration and vision.

Observation is developed by singleness of glance. For instance, if I look at a person, I can see that one person much better than if I looked at many persons. It is like this with everything in life. The first step in learning mysticism is just this to develop our observation. We are always looking at a hundred thousand things around us, and never study one properly at all. To understand and know a thing better you keep looking at it. If you keep looking at everything, you look at nothing! Such is the "law of observation."
The next step - concentration - implies steadiness of mind. You cannot concentrate until you have made the external part steady. Just think! Can you keep your eye in one place for a few moments, without moving it? Can you sit in one posture without fidgeting? Why, you cannot sit still even for a photographer. This shows us that the vehicle given us to control and utilize is not completely in our power. If the lowest vehicle we have is not in our power, though this is the simplest thing to control, how can our mind be in our control? How can we acquire more pure and more powerful thoughts?

Various postures have been recommended to enable a person to acquire control. The body has to be made one's obedient servant first. When the body has been subdued, the mind will learn obedience from it, because order teaches order. The inner self cannot be in order if the external self is not in order - for our mind is always affected by the body.
The third step is vision. When concentration has been mastered, the vision is clear. When the vision is clear, you can aim clearly, like a person who has learnt to aim a ball at a certain spot, and hit it. If he does not throw the ball properly how can it reach the goal? To hold the ball in one's hand and aim it at and hit the desired goal, one must master three things - observation, concentration and vision.