It is also obvious, that this emotion rests not here, but making us cast our view on every side, comprehends whatever objects are connected with its original one by the relation of cause and effect.
Here then reasoning takes place to discover this relation; and according as our reasoning varies, our actions receive a subsequent variation.

But it is evident in this case that the impulse arises not from reason, but is only directed by it.

It is from the prospect of pain or pleasure that the aversion or propensity arises towards any object: And these emotions extend themselves to the causes and effects of that object, as they are pointed out to us by reason and experience.

It can never in the least concern us to know, that such objects are causes, and such others effects, if both the causes and effects be indifferent to us.

Where the objects themselves do not affect us, their connexion can never give them any influence; and it is plain, that as reason is nothing but the discovery of this connexion, it cannot be by its means that the objects are able to affect us.
Since reason alone can never produce any action, or give rise to volition, I infer, that the same faculty is as incapable of preventing volition, or of disputing the preference with any passion or emotion.
This consequence is necessary.