Imagine large enough for you to stand inside
Imagine a giant ball, clear, large enough for you to stand inside. You walk, you run, you fall, you figure out how to direct it just about where you want it to go. Now imagine the ball is many times larger and there are a dozen of you running around inside. Now imagine another increase, and this time there are 7 billion of you inside this ball. Behold, the earth.
:- Doug.