No wonder, then, the imagination returns back again attended with the related passions of love and hatred.

This is not a contradiction, but an exception to the rule; and an exception that arises from the same reason with the rule itself.
Such an exception as this is, therefore, rather a confirmation of the rule.

And indeed, if we consider all the eight experiments I have explained, we shall find that the same principle appears in all of them, and that it is by means of a transition arising from a double relation of impressions and ideas, pride and humility, love and hatred are produced.

An object without [First Experiment.] a relation, or [Second and Third Experiments] with but one, never produces either of these passions; and it is [Fourth Experiment.] found that the passion always varies in conformity to the relation.

Nay we may observe, that where the relation, by any particular circumstance, has not its usual effect of producing a transition either of [Sixth Experiment.] ideas or of impressions, it ceases to operate upon the passions, and gives rise neither to pride nor love, humility nor hatred.