Thus there is a direct and total opposition betwixt our reason and our senses; or more properly speaking, betwixt those conclusions we form from cause and effect, and those that persuade us of the continued and independent existence of body. When we reason from cause and effect, we conclude, that neither colour, sound, taste, nor smell have a continued and independent existence. When we exclude these sensible qualities there remains nothing in the universe, which has such an existence. SECT. V. OF THE IMMATERIALITY OF THE SOUL. Having found such contradictions and difficulties in every system concerning external objects, and in the idea of matter, which we fancy so clear and determinate, We shall naturally expect still greater difficulties and contradictions in every hypothesis concerning our internal perceptions, and the nature of the mind, which we are apt to imagine so much more obscure, and uncertain. But in this we should deceive ourselves. The intellectual world, though involved in infinite obscurities, is not perplexed with any such contradictions, as those we have discovered in the natural. What is known concerning it, agrees with itself; and what is unknown, we must be contented to leave so. It is true, would we hearken to certain philosophers, they promise to diminish our ignorance; but I am afraid it is at the hazard of running us into contradictions, from which the subject is of itself exempted. These philosophers are the curious reasoners concerning the material or immaterial substances, in which they suppose our perceptions to inhere. In order to put a stop to these endless cavils on both sides, I know no better method, than to ask these philosophers in a few words, What they mean by substance and inhesion? And after they have answered this question, it will then be reasonable, and not till then, to enter seriously into the dispute. This question we have found impossible to be answered with regard to matter and body: But besides that in the case of the mind, it labours under all the same difficulties, it is burthened with some additional ones, which are peculiar to that subject. As every idea is derived from a precedent impression, had we any idea of the substance of our minds, we must also have an impression of it; which is very difficult, if not impossible, to be conceived. For how can an impression represent a substance, otherwise than by resembling it? And how can an impression resemble a substance, since, according to this philosophy, it is not a substance, and has none of the peculiar qualities or characteristics of a substance?