THE STARS CONTAIN NOT ONLY FIRE, BUT TANGIBLE EARTH. 6. Is the heaven composed exclusively of fire? Does the fire allow any of its substance to flow off, or escape? Does it, therefore, need being fed? (Plato[213]) thinks the body of the universe is composed of earth and fire; fire to explain its being visible, and earth to explain its being tangible. This would lead us to suppose that the stars are composed of fire not exclusively, but predominatingly, since they seem to possess a tangible element. This opinion is plausible because Plato supports it with reasonable grounds. Sense, sight and touch would lead us to believe that the greater part, if not the whole, of the heaven, is fire. But reason suggests that the heaven also contains earth, because without earth it could not be tangible.[214] This however does not imply that it contains also air and water. It would seem absurd to think that water could subsist in so great a fire; nor could air survive therein without immediately being transformed to steam. It might be objected that two solids which play the parts of extremes in a proportion, cannot be united without two means.[213] This objection, however, might have no cogency, for this mathematical relation might not apply to natural things, as indeed we are led to surmise by the possibility of mingling earth and water without any intermediary. To this it may be answered that earth and water already contain the other elements. Some persons might think that the latter could not effectually unite earth and water; but this would not disturb our contention that the earth and water are related because each of these two elements contains all the others. EARTH CONTAINS ALL THE OTHER ELEMENTS.