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250 the cause or effect of any thing; which evidently gives the advantage to the materialists above their antagonists. To pronounce, then, the final decision upon the whole; the question concerning the substance of the soul is absolutely unintelligible: All our perceptions are not susceptible of a local union, either with what is extended or unextended; there being some of them of the one kind, and some of the other: And as the constant conjunction of objects constitutes the very essence of cause and effect, matter and motion may often be regarded as the causes of thought, as far as we have any notion of that relation.

'Tis certainly a kind of indignity to philosophy, whose sovereign authority ought every where to be acknowledge'd, to oblige her on every occasion to make apologies for her conclusions, and justify herself to every particular art and science, which may be offended at her. This puts one in mind of a king arraign'd for high-treason against his subjects. There is only one occasion, when philosophy will think it necessary and even honourable to justify herself, and that is, when religion may seem to be in the least offended; whose rights are as dear to her as her own, and are indeed the same. If any one, therefore, shou'd imagine that the foregoing arguments are any ways dangerous to religion, I hope the following apology will remove his apprehensions.

There is no foundation for any conclusion a priori either concerning the operations or duration of any object, of which 'tis possible for the human mind to form a conception. Any object may be imagin'd to become entirely inactive, or to be annihilated in a moment; and 'tis an evident principle, that whatever we can imagine, is possible. Now this is no more true of matter, than of spirit; of an extended compounded substance, than of a simple and unextended. In both cases the metaphysical arguments for the immortality of the soul are equally inconclusive; and in both cases the moral arguments and those deriv'd from the analogy of nature are equally strong and convincing. If my philosophy, therefore,