"Because scientific models are not meant to be totally correct, we must always remember the assumptions on which they were based. If we begin to think a model is true, it can mislead us instead of helping us. The celestial sphere, for instance, can help us think of the sky, but we must remember that it is only a mental crutch. The universe is much larger, and more interesting than this ancient scientific model for the heavens."
-- Seeds, Michael A. Astronomy: The Solar System and Beyond., p.14
