Thus, because the gravity of a body encreases or diminishes by the encrease or diminution of its parts, we conclude that each part contains this quality and contributes to the gravity of the whole.

The absence or presence of a part of the cause is attended with that of a proportionable part of the effect.

This connexion or constant conjunction sufficiently proves the one part to be the cause of the other.

As the belief which we have of any event, encreases or diminishes according to the number of chances or past experiments, it is to be considered as a compounded effect, of which each part arises from a proportionable number of chances or experiments.
Let us now join these three observations, and see what conclusion we can draw from them.

To every probability there is an opposite possibility.
This possibility is composed of parts, that are entirely of the same nature with those of the probability; and consequently have the same influence on the mind and understanding.