Shiva means the auspicious. That auspicious quality arises from his immense power to destroy the impurities and transform the mind and body. Hence, he is regarded as the purifier, healer and liberator both in the macrocosm of the universe and the microcosm of the beings.
Shiva is also the sustainer of life. By His mere presence, the world comes to life and so also the beings. As long as he is present in it as its sustainer, the body is lively, pure and auspicious. When He departs from it, it becomes impure and lifeless. So is the case with the whole creation. When he withdraws his power from matter, all movements (chetana) come to an end and with that creation itself.
Shiva is Isvara, the lord of the universe. He is also the source of Prana. Hence, he is known as Prananatha or Pranesvara. In that role, he symbolizes the breathing body and all the Prana in creation.
The Upanishads, extol Prana as the lord of the body. They identify five types of Prana that flows in it, which correspond with the five aspects of Shiva known as Panchanana Shiva.
In the development of Vedic belief system, Prana was originally equated with Atman, the Self or the soul. Atman means the breathing one. The soul is the breathing one because when it is absent, the body cannot breathe. Further, when the mind and the senses are fully withdrawn, one still keeps breathing.
The Upanishads explain why Prana or breath is considered superior to all other organs in the body. It is because they all depend upon Prana for nourishment, while Prana does not depend upon them.
Secondly, all the organs in the body are subject to desires. They can be used or misused according to desires.
However, breath is different. It is not swayed by desires. It works autonomously, without your permission or your will.
Since it is independent and free from desires, breath is considered the purifier and destroyer of bodily impurities.
Breath also plays an important role in restraining the mind and senses. Since, breath is a controller, auspicious, and life sustaining, it is equated with the Shiva (self) in the body.
A body without the presence of prana is a body without Shiva. Hence, it is called Shava, a body without Prana or Shiva.
It is impure and inauspicious. Hence, those who visit funeral grounds or those who touch a dead body are considered impure and required to take a bath before entering their homes or performing any other functions.
According to our scriptures, the whole universe is suffused with the Prana of Shiva. Hence, a devotee believes that he is constantly in touch with Shiva in his own body. Shiva or the Self is not only the breathing one but also the breath itself. By his mere presence, one becomes full of life and energy.
Because of his association with Prana, Shiva is also considered the personification of the sacred sound of Aum. Hence, he is called Omkareswar. Aum is the sacred sound which represents the fourfold reality or consciousness, just as Shiva.
Aum is also known as Pranava and the sound of Aum is called Pranavanada. Pranavanada is verily the sound one makes during breathing. It is truly the sound of breath or prana. Next time, when you are in meditation, focus upon your breath and see how it sounds very much like Aum.
This is true. When you are breathing, with each breath, you are unknowingly and naturally emitting the sound of Aum. With your inbreath, you draw Prana from Shiva, and with the outbreath you return it to him.
Thus, you may not know, but you have an inseparable connection with Shiva. As long as a person is alive he is continuously connected to Shiva through breath. At the same time, he continuously chants the sacred syllable Aum, without even knowing it.
Indeed, all the Jivas or living beings in creation are inseparable from Shiva. They are forever united with him physically through Prana, mentally through their minds and spiritually through their souls.
Therefore, when you breathe, keep remembering the auspicious Shiva. Become aware of the sound of Aum hidden in your breathing and concentrate upon it without any distraction. That sound reminds you that the source of your life and your prana is Shiva himself. That sound will eventually remove your delusion, egoism and bondage and carry you to the abode of Shiva.