Thus, all the internal principles that are necessary in us to produce either pride or humility, are common to all creatures; and since the causes, which excite these passions, are likewise the same, we may justly conclude, that these causes operate after the same _manner_ through the whole animal creation. My hypothesis is so simple, and supposes so little reflection and judgment, that 'tis applicable to every sensible creature; which must not only be allowed to be a convincing proof of its veracity, but, I am confident, will be found an objection to every other system. PART II. OF LOVE AND HATRED. SECTION I. OF THE OBJECT AND CAUSES OF LOVE AND HATRED. 'Tis altogether impossible to give any definition of the passions of _love_ and _hatred_; and that because they produce merely a simple impression, without any mixture or composition. 'Twould be as unnecessary to attempt any description of them, drawn from their nature, origin, causes, and objects; and that both because these are the subjects of our present inquiry, and because these passions of themselves are sufficiently known from our common feeling and experience. This we have already observed concerning pride and humility, and here repeat it concerning love and hatred; and, indeed, there is so great a resemblance betwixt these two sets of passions, that we shall be obliged to begin with a kind of abridgment of our reasonings concerning the former, in order to explain the latter. As the immediate _object_ of pride and humility is self, or that identical person of whose thoughts, actions and sensations, we are intimately conscious; so the _object_ of love and hatred is some other person, of whose thoughts, actions and sensations, we are not conscious. This is sufficiently evident from experience. Our love and hatred are always directed to some sensible being external to us; and when we talk of _self-love_, 'tis not in a proper sense, nor has the sensation it produces any thing in common with that tender emotion, which is excited by a friend or mistress. 'Tis the same case with hatred. We may be mortified by our own faults and follies; but never feel any anger or hatred, except from the injuries of others. But though the object of love and hatred be always some other person, 'tis plain that the object is not, properly speaking, the _cause_ of these passions, or alone sufficient to excite them. For since love and hatred are directly contrary in their sensation, and have the same object in common, if that object were also their cause, it would produce these opposite passions in an equal degree; and as they must, from the very first moment, destroy each other, none of them would ever be able to make its appearance. There must, therefore, be some cause different from the object.