PLATO POSTULATED THE EXISTENCE OF EARTH AS BASIS OF LIFE.
7. Plato's view[217] is to be accepted. The universe must contain something solid, impenetrable, so that the earth, when established in the middle of the universe, might offer a firm foundation for all the animals that walk on it, and that these animals might possess a certain solidity by the very fact of their terrestriality; so that the earth might, by itself, possess the property of continuousness; that it might be illuminated by fire, might also participate in water, so as not to be desiccated, and so that its parts might unite, and that the air might somewhat lighten its mass.