objects, or run from them to others; and in whatever form or order we survey them, the act of the mind exceeds not a simple conception; and the only remarkable difference, which occurs on this occasion, is, when we join belief to the conception, and are persuaded of the truth of what we conceive. This act of the mind has never yet been explained by any philosopher; and therefore I am at liberty to propose my hypothesis concerning it; which is, that 'tis only a strong and steady conception of any idea, and such as approaches in some measure to an immediate impression. SECTION VIII. OF THE CAUSES OF BELIEF. Having thus explained the nature of belief, and shown that it consists in a lively idea related to a present impression; let us now proceed to examine from what principles it is derived, and what bestows the vivacity on the idea. I would willingly establish it as a general maxim in the science of human nature, _that when any impression becomes present to us, it not only transports the mind to such ideas as are related to it, but likewise communicates to them a share of its force and vivacity_. All the operations of the mind depend, in a great measure, on its disposition when it performs them; and according as the spirits are more or less elevated, and the attention more or less fixed, the action will always have more or less vigour and vivacity. When, therefore, any object is presented which elevates and enlivens the thought, every action, to which the mind applies itself, will be more strong and vivid, as long as that disposition continues. Now, 'tis evident the continuance of the disposition depends entirely on the objects about which the mind is employed; and that any new object naturally gives a new direction to the spirits, and changes the disposition; as on the contrary, when the mind fixes constantly on the same object, or passes easily and insensibly along related objects, the disposition has a much longer duration. Hence it happens, that when the mind is once enlivened by a present impression, it proceeds to form a more lively idea of the related objects, by a natural transition of the disposition from the one to the other. The change of the objects is so easy, that the mind is scarce sensible of it, but applies itself to the conception of the related idea with all the force and vivacity it acquired from the present impression.