By them we learn to distinguish the accidental circumstances from the efficacious causes; and when we find that an effect can be produced without the concurrence of any particular circumstance, we conclude that that circumstance makes not a part of the efficacious cause, however frequently conjoined with it.

But as this frequent conjunction necessity makes it have some effect on the imagination, in spite of the opposite conclusion from general rules, the opposition of these two principles produces a contrariety in our thoughts, and causes us to ascribe the one inference to our judgment, and the other to our imagination.

The general rule is attributed to our judgment; as being more extensive and constant.

The exception to the imagination, as being more capricious and uncertain.
Thus our general rules are in a manner set in opposition to each other.
When an object appears, that resembles any cause in very considerable circumstances, the imagination naturally carries us to a lively conception of the usual effect, Though the object be different in the most material and most efficacious circumstances from that cause.

Here is the first influence of general rules.