With reference to yoga prana can be described as something that flows continuously from somewhere inside us, filling us and keeping us alive: it is vitality. In this image, the prana streams out from the center through the whole body. Pranayama is the measuring, control, and directing of the breath, and thus of energy within the organism, in order to restore and maintain health and to promote evolution.

When you are troubled, restless, or confused, you have more prana outside the body than within. When you feel unwell; the quality of prana and its density within the body is reduced. Too little prana in the body can be expressed as a feeling of being stuck or restricted. It can also show as a lack of drive or motivation to do anything; you are listless or even depressed. We may suffer from physical ailments when prana is lacking in the body. Yoga Sutra mentions disturbances in the breath, which can take very different forms. On the other hand, the more peaceful and well-balanced we are, the less our prana is dispersed outside the body. And if all the prana is within the body, we are free of these symptoms.

If prana does not find sufficient room in the body there can be only one reason: it is being forced out by something that really does not belong there-such as blockages caused by rubbish. When we practice pranayama, we try to reduce this rubbish and replace it with more and more prana within the body.

Our state of mind is closely linked to the quality of prana within. The more content a person is and the better he or she feels, the more prana is inside. The more disturbed a person is, the more prana is dissipated and lost. Because we can influence the flow of prana through the flow of our breath, the quality of our breath influences our state of mind and vice versa. In yoga we are trying to make use of these connections so that prana concentrates and can freely flow within us. One definition of the word yogi is "one whose prana is all within his body." In pranayama we want to reduce the amount of prana outside the body until there is none leaking out.

Prana is power. Proper acts of breathing are ways of harnessing that power. It gives control of breathing processes and control of vital force. Even though, in breathing, fresh air from outside the body enters the body and foul air leaves, mystical pranayama conceives appropriation of power as a bringing to conscious manifestation an omnipresent cosmic power which exists already latent within oneself as a particular expression of cosmic being. When a person attains a feeling of oneness with the rest of the universe, his anxiety tends to disappear. When the in-flowing breath is neutralized or joined with the out-flowing breath, then perfect relaxation and balance of body activities are realized. In yoga, we are concerned with balancing the flows of vital forces, then directing them inward to the chakra system and upward to the crown chakra or thousand petalled lotus (sahasara). When one acquires an intuitive apprehension of ultimate power and of his own identity with it, he loses his fear of external powers and develops a trust which is conducive to confident living.

Whatever happens in the mind influences the breath; the breath becomes quicker when we are excited and deeper and quieter when we relax. In order to influence our prana we must be able to influence the mind. Our actions often disturb the mind, causing prana to exude from the body. Through daily pranayama practice we reverse this process, as a change in the breathing pattern influences the mind.

The idea of prana existing within or beyond the body can be understood as a symbol for our state of mind. When the mind is as clear as transparent glass there is nothing that could disturb the body; there is no rubbish lying about. On the other hand, if we notice hesitancy, discontent, fear of doing something because it might be inappropriate, and so forth, we can assume that there are blockages in the system. These blockages do not just occur in the physical body; they exist even more in the mind, in consciousness. Every kind of rubbish we find in ourselves was originally produced by incorrect knowledge.

The link between mind and breath is most significant. The Yoga Sutra says that when we practice pranayama the veil is gradually drawn away from the mind and there is growing clarity. The mind becomes ready for deep meditations. Thus, pranayama is first and foremost awareness of the breath. Here, we focus our attention on the breath. In the practice of pranayama it is therefore very important to keep an alert mind, for the processes that are being observed are very subtle. There is no visible movement of the body as in asana practice; we must acutely sense and feel the movement of the breath within. The only dynamic process is breathing. Patanjali makes a few practical suggestions for keeping our attention on the breath. For example, we can focus on where it enters and leaves the body at the nostrils. It is also possible to listen to the breath, especially if you make a slight noise by gently contracting the vocal chords, a pranayama technique known as ujjayi. Or we can follow the areas through which the air passes through.

The goal of pranayama is not to bring the inhalation and exhalation into a certain relationship with each other, or to establish a particular length of breath. The various practices of pranayama gives us many different possibilities for following the breath. When we follow the breath, the mind will be drawn into the activities of the breath. In this way pranayama prepares us for the stillness of meditation.

The breath relates directly to the mind and to our prana. Prana enters the body in the moment when there is a positive change in the mind. It is true that our state of mind does not alter with every in-breath or out-breath. The change occurs over a long period of time. If we are practicing pranayama and notice a change of mind, then prana has long before entered the body. The proof of the pudding is in our relationships with others. It tells us whether we had a positive changes in the mind and whether we actually understand ourselves better.

Without prana there is no life. We can imagine that prana flows into us as we inhale, but prana is also the power behind breathing out. As well, prana is transformed in the body into various powers, and is involved in processes that ensure that we rid ourselves of what we no longer need. Out breath is a very important part of the body's elimination processes. We can use out breath as a mechanism to free the mind from blocks and thereby lead us to greater clarity.

Pranayama or breathing technique is very important in yoga. It goes hand in hand with the asana or pose. In the Yoga Sutras, the practices of pranayama and asana are considered to be the highest form of purification and self discipline for the mind and the body, respectively. The practices produce the actual physical sensation of heat, called tapas, or the inner fire of purification. It is taught that this heat is part of the process of purifying the nadis, or subtle nerve channels of the body. This allows a more healthful state to be experienced and allows the mind to become more calm.

In pranayama we focus our attention on the breath. In the practice of pranayama it is therefore very important to keep an alert mind, for the processes that are being observed are very subtle. There is no visible movement of the body as in asana practice; we must acutely sense and feel the movement of the breath within. The only dynamic process is breathing. Patanjali makes a few practical suggestions for keeping our attention on the breath. For example, we can focus on a place in the body where we can feel or hear the breath. Or we can try to follow the movement of the breath in the body, feeling the inhalation from the center of the collarbone, down through the rib cage to the diaphragm, and following the exhale upward from the abdomen. Another means for paying attention to the breath is to feel where it enters and leaves the body at the nostrils. It is also possible to listen to the breath, especially if you make a slight noise by gently contracting the vocal chords, a pranayama technique known as ujjayi.

Suggestions like these help us keep our attention on the breath and prevent our practice from becoming merely mechanical. The goal of pranayama is not to bring the inhalation and exhalation into a certain relationship with each other, or to establish a particular length of breath. If exercises such as these help us concentrate on our pranayama, that is wonderful. But the true aim of the various techniques and breath ratios of breathing in pranayama is first and foremost to give us many different possibilities for following the breath. When we follow the breath, the mind will be drawn into the activities of the breath. In this way pranayama prepares us for the stillness of meditation.

The breath relates directly to the mind and to our prana, but we should not therefore imagine that as we inhale, prana simply flows into us. This is not the case. Prana enters the body in the moment when there is a positive change in the mind. Of course, our state of mind does not alter with every in-breath or outbreath; change occurs over a long period of time. If we are practicing pranayama and notice a change of mind, then prana has long before entered the body. Changes of mind can be observed primarily in our relationships with other people. Relationships are the real test of whether we actually understand ourselves better.

That which enters the body is called prana and that which leaves it is called apana. The term apana also refers to the region of the lower abdomen and all the activities that take place there. Apana describes that part of prana that has the function of elimination and provides the energy for it, and it also refers to the lower belly and the rubbish that collects there when the power of prana is not in a state of equilibrium. When a person is slow and heavy we sometimes say that he has too much apana. Apana as pranic energy is something we need, but apana as refuse left from activating this energy actually prevents prana from developing within. All forms of prana are necessary, but to be effective they must be in a state of balance with each other. If someone has a lot of rubbish in the region of the lower abdomen then he or she consumes too much energy there, and this imbalance should be addressed. The goal is to reduce apana to an efficient minimum.

Apana as waste matter accumulates because of many factors, some of which lie within our control. The practice of yoga aims to reduce these impurities. People who are short of breath, cannot hold their breath, or cannot exhale slowly are seen as having more apana, whereas those who have good breath control are considered to have less apana. An overabundance of apana leads to problems in all areas of the body. We have to reduce the apana so that we can bring more prana into the body.

When we inhale, prana from outside the body is brought within. During inhalation, prana meets apana. During exhalation, the apana within the body moves toward the prana. Pranayama is the movement of the prana toward the apana and the movement of the apana toward the prana. Similarly, holding the breath after inhalation moves the prana toward the apana and holds it there. Holding the breath after exhalation moves the apana toward the prana.

What happens within this movement of prana and apana? According to yoga we have a fire, agni, in the body, situated in the vicinity of the navel, between the prana-vayu and the apana-vayu. The flame itself is constantly changing direction: on inhalation the breath moves toward the belly, causing a draft that directs the flame downward like in a fireplace; during exhalation the draft moves the flame in the opposite direction, bringing with it the just-burned waste matter. It is not enough to burn the rubbish; we must also rid the body of it. A breathing pattern where the exhalation is twice as long as the inhalation is aimed at providing more time during exhalation for freeing the body of its blockages. Everything we do to reduce the rubbish in the body is a step in the direction of releasing our blockages. With the next inhalation we bring the flame back to the apana. If all the previously burned waste has not left the body, the flame will lose some of its power.

Certain physical positions are beneficial for the meeting of fire and rubbish. In all inverted postures, the agni is directed toward the apana. This is the reason yoga attributes so much significance to the cleansing effects of inverted postures. Cleansing is intensified when we combine inverted postures with pranayama techniques.

All aspects of pranayama work together to rid the body of apana so that prana can find more room within. In the moment when waste is released, prana fills the space in the body where it really belongs. Prana has its own movement; it cannot be controlled. What we can do is create the conditions in which prana may enter the body and permeate it.

The beauty of prana is that through this, we can influence purusa, the essence of life. Yoga suggests that we can influence prana via our breath and mind. By working with these through pranayama, we create optimal conditions for the prana to flow freely within.