Newton\:
It\u2019s like this\: actually, the Moon would like to move straight on, because that is its natural movement \u2014 always straight on and always constant for all eternity, or at least until some external force stops it from moving in this way. This is what I have called the principle of inertia. Then, gravity comes along and pulls the Moon down a little. At the same time, however, the Moon strives to go straight on, and then falls down a little bit more towards the Earth because of its gravity. The result of this zigzagging, which happens so fast that you don\u2019t see it, is the Moon\u2019s near-circular orbit.
Aristotle\:
Why keep it simple when you can have it complicated\! It is as though the Moon were a slave and gravity a sort of shackle.