Tis much better to do a little with certainty & leave the rest for others that come after than to explain all things by conjecture without making sure of any thing.
It is reasonable that forces directed toward bodies depend on the nature and the quantity of matter of such bodies, as happens in the case of magnetic bodies.
I keep the subject of my inquiry constantly before me, and wait till the first dawning opens gradually, by little and little, into a full and clear light.
