a very cogent question presents itself on this occasion: if this distinct substance that is said to form one of the component parts of man, be really what it is reported, and if it be not, it is not what it is described; if it be unknown, if it be not pervious to the senses; if it be invisible, by what means did the metaphysicians themselves become acquainted with it? How did they form ideas of a substance, that taking their own account of it, is not, under any of its circumstances, either directly or by analogy, cognizable to the mind of man? If they could positively achieve this, there would no longer be any mystery in Nature: it would be as easy to conceive the time when all was nothing, when all shall have passed away, to account for the production of every thing we behold, as to dig in a garden or read a lecture.—Doubt would vanish from the human species; there could no longer be any difference of opinion, since all must necessarily be of one mind on a subject so accessible to every enquirer.
But it will be replied, the materialist himself admits, the natural philosophers of all ages have admitted, elements and atoms, beings simple and indivisible, of which bodies are composed:—granted; they have no more: they have also admitted that many of these atoms, many of these elements, if not all, are unknown to them: nevertheless, these simple beings, these atoms of the materialist, are not the same thing with the spirit, or the soul of the metaphysician. When the natural philosopher talks of atoms—when he describes them as simple beings, he indicates nothing more than that they are homogeneous, pure, without mixture: but then he allows that they have extent, consequently parts,
