The ash of any burnt object is not regarded as holy ash. Bhasma (the holy ash) is the ash from the homa (sacrificial fire) where special wood along with ghee (clarified butter) and other herbs is offered as worship of the Lord. Or the deity is worshipped by pouring ash as abhiseka and is then distributed as Bhasma.
Bhasma is generally applied on the forehead. Some apply it on certain parts of the body like the upper arms, chest etc. Some ascetics rub it all over the body. Many consume a pinch of it each time they receive it.
Why do we use Bhsma?
The application of Bhsma signifies destruction of the evil and remembrance of the divine. Bha – bhartsanam -(to destroy) and sma – smaranam – (to remember). B/mmm is called vibhuti (which means glory) as it gives glory to one who applies it and raksha (which means protection) as it protects the wearer from ill health and evil, by purifying him or her.
Homa (offering of oblations into the fire with sacred chants) signifies the offering or surrender of the ego and egocentric desires into the flame of knowledge for a noble and selfless cause. The consequent ash signifies the purity of the mind, which results from such actions. Also the fire of knowledge burns the oblation and wood signifying ignorance and inertia respectively. The ash we apply indicates that we should burn false identification with the body and become free of the limitations of birth and death. The application of ash also reminds us that the body is perishable and shall one day be reduced to ashes. We should therefore not get too attached to it. Death can come at any moment and this awareness must increase our drive to make the best use of time.
Bhasma is specially associated with Lord Shiva who applies it all over His body. Shiva devotees apply Bhasma as a tripura (the form of three horizontal lines). When applied with a red spot in the center, the mark symbolizes Shiva-Shakti (the unity of energy and matter that creates the entire seen and unseen universe).
Ash is what remains when all the wood is burnt away and it does not decay. Similarly, the Lord is the imperishable. Truth that remains when the entire creation of innumerable names and forms is dissolved.
Bhasma has medicinal value and is used in many ayurvedic medicines. The Upanishad say that the famous Maha Mrutyunjaya mantra should be chanted whilst applying ash on the forehead.
ॐ त्र्यम्बकं यजामहे सुगन्धिंम् पुष्टिवर्धनम् ।
उर्वारुकमिव बन्धनान् मृत्योर्मुक्षीय मामृतात् ।।
Om, tryambakam yaiaamahc sugandhim pushtivardhanam,
urvaa rukamiva bandhanaan mrytyor muksheeyarnaa amrutaat
We worship the three-eyed Lord Shiva Who nourishes and spreads fragrance in our lives. May He free us from the shackles of sorrow, change and death – effortlessly, like the fall of a ripe cucumber from its stem and bestow immortality.
Swamini Vimalananda, Radhika Krishnakumar