A treatise of human nature: being an attempt to introduce the experimental method of reasoning into moral subjects. ... [pt.3]
Hume, David, 1711-1776.

To be inserted Vol. I. page 174. line 8. after these words (according to the foregoing definition.) beginning a new paragraph.

THIS operation of the mind, which forms the belief of any matter of fact, seems hitherto to have been one of the greatest mysteries of philosophy; tho' no one has so much as suspected, that there was any diffi∣culty in explaining it. For my part I must own, that I find a considerable difficulty in the case; and that even when I think I understand the subject perfectly, I am at a Page  293 loss for terms to express my meaning. I conclude, by an induction which seems to me very evident, that an opinion or belief is nothing but an idea, that is different from a fiction, not in the nature, or the order of its parts, but in the manner of its being con∣ceiv'd. But when I wou'd explain this man∣ner, I scarce find any word that fully an∣swers the case, but am oblig'd to have re∣course to every one's feeling, in order to give him a perfect notion of this operation of the mind. An idea assented to feels different from a fictitious idea, that the fancy alone presents to us: And this different feeling I endeavour to explain by calling it a superior force, or vivacity, or solidity, or firmness, or steadiness. This variety of terms, which may seem so unphilosophical, is intended only to express that act of the mind, which renders realities more present to us than fictions, causes them to weigh more in the thought, and gives them a superior influence on the passions and imagination. Provided we agree about the thing, 'tis needless to dispute about the terms. The imagination has the com∣mand over all its ideas, and can join, and mix, and vary them in all the ways possible. It may conceive objects with all the circum∣stances of place and time. It may set them, Page  294 in a manner, before our eyes in their true colours, just as they might have existed. But as it is impossible, that that faculty can ever, of itself, reach belief, 'tis evident, that belief consists not in the nature and order of our ideas, but in the manner of their con∣ception, and in their feeling to the mind. I confess, that 'tis impossible to explain per∣fectly this feeling or manner of conception. We may make use of words, that express something near it. But its true and proper name is belief, which is a term that every one sufficiently understands in common life. And in philosophy we can go no farther, than assert, that it is something felt by the mind, which distinguishes the ideas of the judgment from the fictions of the imagina∣tion. It gives them more force and influ∣ence; makes them appear of greater im∣portance; infixes them in the mind; and renders them the governing principles of all our actions.