I. It is an acknowledged truth, that every kind of act whatever, and consequently every kind of offense, is apt to assume a different character, and be attended with different effects, according to the nature of the motive which gives birth to it. This makes it requisite to take a view of the several motives by which human conduct is liable to be influenced.

II. By a motive, in the most extensive sense in which the word is ever used with reference to a thinking being, is meant any thing that can contribute to give birth to, or even to prevent, any kind of action. Now the actions of a thinking being is the act either of the body, or only of the mind: and an act of the mind is an act either of the intellectual faculty, or of the will. Acts of the intellectual faculty will sometimes rest in the understanding merely, without exerting any influence in the production of any acts of the will. Motives, which are not of a nature to influence any other acts than those, may be styled purely speculative motives, or motives resting in speculation. But as to these acts, neither do they exercise any influence over external acts, or over their consequences, nor consequently over any pain or any pleasure that may be in the number of such consequences. Now it is only on account of their tendency to produce either pain or pleasure, that any acts can be material. With acts, therefore, that rest purely in the understanding, we have not here any concern: nor therefore with any object, if any such there be, which, in the character of a motive, can have no influence on any other acts than those.

III. The motives with which alone we have any concern are such as are of a nature to act upon the will. By a motive then, in this sense of the word, ls to be understood any thing whatsoever, which, by influencing the will of a sensitive being, is supposed to serve as a means of determining him to act, or voluntarily to forbear to act, upon any occasion. Motives of this sort, in contradistinction to the former, may be styled practical motives, or motives applying to practice.

IV. Owing to the poverty and unsettled state of language, the word motive is employed indiscriminately to denote two kinds of objects, which, for the better understanding of the subject, it is necessary should be distinguished. On some occasions it is employed to denote any of those really existing incidents from whence the act in question is supposed to take its rise. The sense it bears on these occasions may be styled its literal or unfigurative sense. On other occasions it is employed to denote a certain fictitious entity, a passion, an affection of the mind, an ideal being which upon the happening of any such incident is considered as operating upon the mind, and prompting it to take that course, towards which it is impelled by the influence of such incident. Motives of this class are Avarice, Indolence, Benevolence, and so forth; as we shall see more particularly farther on. This latter may be styled the figurative sense of the term motive.

V. As to the real incidents to which the name of motive is also given, these too are of two very different kinds. They may be either, 1. The internal perception of any individual lot of pleasure or pain, the expectation of which is looked upon as calculated to determine you to act in such or such a manner; as the pleasure of acquiring such a sum of money, the pain of exerting yourself on such an occasion, and so forth: or, 2. Any external event, the happening whereof is regarded as having a tendency to bring about the perception of such pleasure or such pain; for instance, the coming up of a lottery ticket, by which the possession of the money devolves to you; or the breaking out of a fire in the house you are in, which makes it necessary for you to quit it. The former kind of motives may be termed interior, or internal: the latter exterior, or external.

VI. Two other senses of the term motive need also to be distinguished. Motive refers necessarily to action. It is a pleasure, pain, or other event, that prompts to action. Motive then, in one sense of the word, must be previous to such event. But, for a man to be governed by any motive, he must in every case look beyond that event which is called his action; he must look to the consequences of it: and it is only in this way that the idea of pleasure, of pain, or of any other event, can give birth to it. He must look, therefore, in every case, to some event posterior to the act in contemplation: an event which as yet exists not, but stands only in prospect. Now, as it is in all cases difficult, and in most cases unnecessary, to distinguish between objects so intimately connected, as the posterior possible object which is thug looked forward to, and the present existing object or event which takes place upon a man's looking forward to the other, they are both of them spoken of under the same appellation, motive. To distinguish them, the one first mentioned may be termed a motive in prospect, the other a motive in esse: and under each of these denominations will come as well exterior as internal motives. A fire breaks out in your neighbour's house: you are under apprehension of its extending to your own: you are apprehensive, that if you stay in it, you will be burnt: you accordingly run out of it. This then is the act: the others are all motives to it. The event of the fire's breaking out in your neighbour's house is an external motive, and that in esse: the idea or belief of the probability of the fire's extending to your own house, that of your being burnt if you continue, and the pain you feel at the thought of such a catastrophe, are all so many internal events, but still in esse: the event of the fire's actually extending to your own house, and that of your being actually burnt by it, external motives in prospect: the pain you would feel at seeing your house a burning, and the pain you would feel while you yourself were burning, internal motives in prospect: which events, according as the matter turns out, may come to be in esse: but then of course they will cease to act as motives.

VII. Of all these motives, which stand nearest to the act, to the production of which they all contribute, is that internal motive in esse which consists in the expectation of the internal motive in prospect: the pain or uneasiness you feel at the thoughts of being burnt. All other motives are more or less remote: the motives in prospect, in proportion as the period at which they are expected to happen is more distant from the period at which the act takes place, and consequently later in point of time: the motives in esse, in proportion as they also are more distant from that period, and consequently earlier in point of time.

VIII. It has already been observed, that with motives of which the influence terminates altogether in the understanding, we have nothing here to do. If then, amongst objects that are spoken of as motives with reference to the understanding, there be any which concern us here, it is only in as far as such objects may, through the medium of the understanding, exercise an influence over the will. It is in this way, and in this way only, that any objects, in virtue of any tendency they may have to influence the sentiment of belief, may in a practical sense act in the character of motives. Any objects, by tending to induce a belief concerning the existence, actual, or probable, of a practical motive; that is, concerning the probability of a motive in prospect, or the existence of a motive in esse; may exercise an influence on the will, and rank with those other motives that have been placed under the name of practical. The pointing out of motives such as these, is what we frequently mean when we talk of giving reasons. Your neighbour's house is on fire as before. I observe to you, that at the lower part of your neighbour's house is some wood-work, which joins on to yours; that the flames have caught this wood-work,and so forth; which I do in order to dispose you to believe as I believe, that if you stay in your house much longer you will be burnt. In doing this, then, I suggest motives to your understanding; which motives, by the tendency they have to give birth to or strengthen a pain, which operates upon you in the character of an internal motive in esse, join their force, and act as motives upon the will.