The more experience we collect, the more we shall be convinced that the word _spirit_, in its present received usage, conveys no one sense that is tangible, either to ourselves or to those that invented it; consequently cannot be of the least use, either in physics or morals. What modern metaphysicians believe and understand by the word, is nothing more than an _occult_ power, imagined to explain _occult_ qualities and actions, but which, in fact, explains nothing. Savage nations admit of spirits, to account to themselves for those effects, which to them appear marvellous, as long as their ignorance knows not the cause to which they ought to be attributed. In attributing to spirits the phenomena of Nature, as well as those of the human body, do we, in fact, do any thing more than reason like savages? Man has filled Nature with spirits, because he has almost always been ignorant of the true causes of those effects by which he was astonished. Not being acquainted with the powers of Nature, he has supposed her to be animated by a _great spirit_: not understanding the energy of the human frame, he has in like manner conjectured it to be animated by a _minor spirit_: from this it would appear, that whenever he wished to indicate the unknown cause of a phenomena, he knew not how to explain in a natural manner, he had recourse to the word _spirit_. In short, _spirit_ was a term by which he solved all his doubts, and cleared up his ignorance to himself. It was according to these principles that when the AMERICANS first beheld the terrible effects of gunpowder, they ascribed the cause to wrathful spirits, to their enraged divinities: it was by adopting these principles, that our ancestors believed in a plurality of gods, in ghosts, in genii, &c. Pursuing the same track, we ought to attribute to spirits gravitation, electricity, magnetism, &c. &c. It is somewhat singular, that priests have in all ages so strenuously upheld those systems which time has exploded; that they have appeared to be either the most crafty or the most ignorant of men. Where are now the priests of Apollo, of Juno, of the Sun, and a thousand others? Yet these are the men, who in all times have persecuted those who have been the first to give natural explanations of the phenomena of Nature, as witness ANAXAGORAS, ARISTOTLE, GALLILEO, DESCARTES, &c. &c. CHAP. VIII. _The Intellectual Faculties derived from the Faculty of Feeling_. To convince ourselves that the faculties called _intellectual_, are only certain modes of existence, or determinate manners of acting, which result from the peculiar organization of the body, we have only to analyze them; we shall then see that all the operations which are attributed to the soul, are nothing more than certain modifications of the body; of which a substance that is without extent, that has no parts, that is immaterial, is not susceptible.