But we who live in these hollows are deceived into the notion that we are dwelling above on the surface of the earth; just as if a creature who was at the bottom of the sea were to fancy that he was on the surface of the water, and that the sea was the heaven through which he saw the sun and the other stars… Such is exactly our case: for we are dwelling in a hollow of the earth, and fancy that we are on the surface; and the air we call heaven, in which we imagine that the stars move. But the fact is, that owing to our feebleness and sluggishness we are prevented from reaching the surface of the air: for if any man could arrive at the exterior limit, or take the wings of a bird and come to the top, then like a fish who puts his head out of the water and sees this world, he would see a world beyond.
~ Plato, Phaedo
