4-62 Muhammad ibn al-Hassan - may God be pleased with him - narrated that Muhammad ibn al-Hassan al-Saffar quoted Muhammad ibn al-Hussein ibn Abil Khat’tab, on the authority of Muhammad ibn Sin’an, on the authority of Al-Mufaz’zal ibn Umar, on the authority of Aba Abdullah as-Sadiq (MGB), “Man’s strength and survival depends on four things: fire, light, air and water. Eating and drinking are assisted by fire. Man sees and understands by light. Man hears and smells by air. Man enjoys food and drinks with water. If there was no heat form fire in man’s stomach, he could not digest food or drinks. If there was no light for his eyes, he could not see and understand. If air did not exist, his stomach would not get heated. If water did not exist, he could not enjoy eating food and drinking beverages.”Al-Mufaz’zal ibn Umar added, “I asked the Imam (MGB) about the various types of fire. He (MGB) said, ‘There are four types of fire: fire that eats and drinks; fire that eats but doesn’t drink; fire that drinks but doesn’t eat; and fire that neither eats nor drinks. The first is the fire with which one eats and drinks and that is in men and animals. The fire which eats but doesn’t drink is the fire of wood. The fire that drinks but doesn’t eat is the fire of the trees. The fire that neither eats nor drinks is that of flint stone and a glowworm. ”