XVI. This error is common to all men in their wanderings when they are asleep; because he who dreams, believes he perceives those objects with his senses, which he only perceives with his imagination; and from hence, the rigid sceptics deduce a most pernicious argument, by way of proving, that we should doubt of every thing; because they say no man can be positively certain, whether he is asleep or awake; according to which mode of reasoning, no one can be certain, whether he sees, hears, or touches any thing whatever; for notwithstanding his having the greatest confidence that he is awake, it is possible that he may be sleeping; and that the things which are represented to him as seen, heard, &c. are all imaginary. For example, I consider myself as now writing, and reading what I write. But what certainty have I that I am writing and reading? Have not I dreamed a thousand times, that I was reading and writing? And at those times, such occupations appeared to me, not as things that I was dreaming of, but as exercises that I was really and actually practising; and therefore, that may be the case with me at present. XVII. I have said already, and with reason, that this argument is a most pernicious and dangerous one; for whatever answer you make to it, your adversary turns upon you, and urges the opposite opinion as forcibly, as you can support your reply. At least I have never seen any solution of this matter, which could more or less vanquish the force of the difficulty. It has been objected to this sort of reasoning, that the argument proves too much, and tends to involve in, and reduce to the same state of doubt, all the sacred dogmas of religion. This remark is a just one, for he who comes to doubt, whether all he hears or sees is not a mere imaginary representation, must necessarily doubt of the reality of all the instruction he has received, both with respect to religion, and every other matter. But what advantage shall we gain, by insisting upon this against a sceptic, whose intention perhaps is to destroy all religion? And although he should not argue with this depraved view, but should reply to these objections out of wantonness, or from motives of vanity and ostentation, and a fondness of shewing his parts, it would be wasting time to dispute with him, or to press the argument, because these instances, notwithstanding they are good ones and may be fairly insisted on, are not answers.