To practise Tantra is to plummet into wisdom-fire. The word ‘fire’ is used because fire transforms solidity into emptiness and shows us the empty nature of the material world. Fire is a fascinating element – it’s both tangible and intangible. You can’t pick it up – you can only pick up what it’s burning. It’s intangible and yet it destroys or devours tangibility. It has great power to transform substance, yet it seems to be substanceless. So wisdom-fire as a Tantric term carries the sense in which wisdom; that is to say primordial wisdom, can change the world as we perceive it quite radically. The fire of wisdom can burn away illusion – it can reduce our own hard and substance-orientated concepts to ashes.
p12, Wearing the Body of Visions, Ngakpa Chögyam, Aro Books, 1995, ISBN 1-898185-03-4