[86] But we must examine this question more accurately, in the following manner. There are three species in fire; the coal, and the flame, and the light. Now coal is the fire in its earthy substance, which, like a sort of spiritual habit, couches and lies hid in a sort of cavern, pervading it all to its very extremities. And the flame is that part which, being raised on high, is lifted up from its fuel. And the light is that which is emitted from the flame, so as to co-operate with the eyes, in order to enable them to comprehend what is seen. And the flame occupies the middle position between the coal and the light; for when it is extinguished it ends in coal, and when it is kindled it excites the light, which, being deprived of its burning power, blazes.