In the many references to fire in the alchemical texts we can find the most spiritual and purest – the Secret Fire. This refined heat allow you to change yourself from within. The same way that ordinary metals transmute into gold. With this process we are guided into the deepest part of ourselves, in order to get rid of the corruption responsible for our stagnation.
This sacred element could be associated to Prometheus, the deity who stole the fire (secret) from the Gods and gave it to humans. The Fire was life, true knowledge and understanding.
You should start looking in yourself, digging deeper. Facing memories and desires, confronting our shadow-self, understand who YOU really are. This journey is hard, depressive like an odyssey through the Underworld, defying demons with masks of yourself. What we find there could shock us and drag us to the abyss.