"The Science of yoga is quite simply the science of being in perfect alignment, in absolute harmony, in complete sync with the existence"
The universe is a big mystery, and those who have sought it, have definitely known it. Everything cannot be discovered in labs. The whole understanding of yoga is that, whatever is out there, in the whole universe, is within us too. Just by paying attention to our system, we can explore the mysteries of existence. Even science has come to the understanding that from the biggest of galaxies to the smallest of atoms, everything works the same way, just on a different level of magnitude.
Modern science has come to the understanding that the universe is nothing but energy working in different forms. Yoga has known this for thousands of years. It says that 'prana' is the most fundamental energy in the universe. Whatever we see, within or without, is just a manifestation of prana.
In the human body too, prana has manifested in five different forms. They are known as prana Vayu, Apana Vayu, Samana vayu, udana vayu, and vyana vayu. A whole sect of yoga is devoted towards practices to gain control over these five elements. Gaining control over them, one can gain control over life itself.
Science has been able to understand only this aspect of prana until now. Prana Vayu is what we know as the breath. It is the most fundamental life force within us responsible for our lives. Most of the yogic practices aim towards gaining control over the prana Vayu. That is the reason there are so many breath techniques in yoga known as 'pranayama'.
This Vayu is responsible for the elimination of impurities from our body, mainly for excretion. Yoga puts a great emphasis on a clean bowel. You must have noticed that for yourself that if the bowel isn't clean, we can't work to our fullest, we become lethargic and even thoughts are not clear. With a clean bowel, we feel much more energetic and vibrant. So, with control over Apana vayu, a very clean body could be administered.
This is the vayu responsible for digestion and heat in our bodies. A lot of people suffer digestion problems, just because their Samana isn't working properly. People wonder how yogis could live with no or very little food for days. By gaining over Samana, much energy could be absorbed from even a very low quantity of food. Samana is the same reason yogis could live in the heights of snow-clad Himalayas with no garments. They gain control over the heat produced in the body and can change it as per their needs.
This Vayu is responsible for the working of our sensory organs and consciousness as well. One can gain control over the senses by gaining control over Udana. Those people who are
gifted with extraordinary senses have generally more efficiently working Udana. This is a very important step for yogis to get over the sensory illustrations of the World and access the deeper realms of consciousness.
This is the most important of all five vayus. Vyana is the Vayu that keeps the whole existence together, the millions of stars, galaxies, the infinity of space. Vyana keeps the whole 'you' together if it leaves the body, then what we know as 'ourselves' dies. The whole science of yoga is towards getting to know this element of prana. When one comes to the understanding of vyana, not intellectually, but experientially, then the dualities of life collapse, what we know as 'we' dissolves into the infinity, life becomes a dance, a song, a celebration of the divine.