The absurdity of such inquiries, into any thing more than the mere phenomena, if it be not sufficiently evident of itself, may, perhaps, be rendered more apparent, by a very easy supposition. Let us imagine the permanent unknown substance _matter_, and the permanent unknown substance _mind_, to be rendered, by the same divine power which made them, altogether different in their own absolute essence, as they exist independently, but to exhibit relatively, precisely the same phenomena as at present,--that spring, and summer, and autumn, and winter, in every appearance that can affect our organs of perception, succeed each other as now, pouring out the same profusion of foliage, and flowers, and fruits, and, after the last gladness of the vintage and the harvest, sweeping the few lingering blossoms, with those desolating blasts, which seem like the very destroyers of nature, while they are only leading in, with great freshness, under the same benevolent eye of Heaven, the same delightful circle of beauty and abundance,--that, in mind, the same sensations are excited by the same objects, and are followed by the same remembrances, and comparisons, and hopes, and fears;--in these circumstances, while all the phenomena which we observe, and all the phenomena of which we are conscious, continue exactly the same, can we believe, that we should be able to discover the essential change, which, according to this supposition, had taken place, in the permanent subjects of these unvaried phenomena! And, if, as long as the external and internal phenomena continued exactly the same, we should be incapable of discovering, or even suspecting, the slightest change, where, by supposition, there had been a change so great, how absurd is it to conceive that the changed or unchanged nature of the substance itself, as it exists independently of the phenomenon, ever can become known to us. He, indeed, it may always safely be presumed, knows least of the mind, who thinks that he knows its substance best. “What is the soul?” was a question once put to Marivaux. “I know nothing of it,” he answered, “but that it is spiritual and immortal.” “Well,” said his friend, “let us ask Fontenelle, and _he_ will tell us what it is.” “No,” cried Marivaux, “ask any body but Fontenelle, for he has too much _good sense to know any more about it than we do_.”