Fire is the essence of all existence. Fire is the builder, the preserver and the destroyer. Nothing can exist without fire, it is the very basis of life, from the smallest atom to the fire of cosmos, from purifying to consuming all.
Agni is the Vedic God residing in fire and is mentioned more times in the Vedic hymns than any other deities. He relates to consciousness or awareness, the carrier of the Divine spark, where there is Spirit, there is Agni and is therefore worshiped as the omniscient God.
Agni is the connection between the devotee and the deity, conveying offerings through fire. In ancient times, fire not only provided heat for cooking, warmth and light but also supplied people with their emotional and spiritual connection.
It is of no surprise then that fire plays an important role in the Hindu tradition and is incorporated in almost all rituals and practices. From lighting a diya for prayers to deities, to marriage to the finality of cremation, fire is a constant companion of a Hindu.
Fire is an aspect of the Divine and it is with this in mind, our ancestors refrained us from blowing out a candle or a fire with our breath. We may have heard several reasons on why we should not do so by our parents and grandparents.
The smallest spark of fire represents Agni, the fire God and to blow it out with our breath would be considered impolite and disrespectful to the very basis of connection between us and the Divine.
It is with this reason alone that Hindus extinguish fire either with their hands or using a candle snuffer instead.