DEAR SIR,--I have read over your Dialogue, with all the application I am master of. Though I have never looked into any thing of your writing, which did not either entertain or instruct me; yet, I must freely own to you, that I have received from this last piece an additional satisfaction, and what indeed I have a thousand times wished for in some of your other performances. In the first part of this work, you have given full scope to the native bent of your genius. The ancients and moderns, how opposite soever in other respects, equally combine in favour of the most unbounded scepticism. Principles, customs, and manners, the most contradictory, all seemingly lead to the same end; and agreeably to your laudable practice, the poor reader is left in the most disconsolate state of doubt and uncertainty. When I had got thus far, what do you think were my sentiments? I will not be so candid as to tell you; but how agreeable was my surprise, when I found you had led me into this maze, with no other view, than to point out to me more clearly the direct road. Why can't you always write in this manner? Indulge yourself as much as you will in starting difficulties, and perplexing received opinions: but let us be convinced at length, that you have not less ability to establish true principles, than subtlety to detect false ones. This unphilosophical, or, if you will, this lazy disposition of mine, you are at liberty to treat as you think proper; yet am I no enemy to free inquiry, and I would gladly flatter myself, no slave to prejudice or authority. I admit also that there is no writing or talking of any subject that is of importance enough to become the object of reasoning, without having recourse to some degree of subtlety or refinement. The only question is, where to stop,--how far we can go, and why no farther. To this question I should be extremely happy to receive a satisfactory answer. I can't tell if I shall rightly express what I have just now in my mind: but I often imagine to myself, that I perceive within me a certain instinctive feeling, which shoves away at once all subtle refinements, and tells me with authority, that these air-built notions are inconsistent with life and experience, and, by consequence cannot be true or solid. From this I am led to think, that the speculative principles of our nature ought to go hand in hand with the practical ones; and, for my own part, when the former are so far pushed, as to leave the latter quite out of sight, I am always apt to suspect that we have transgressed our limits. If it should be asked--how far will these practical principles go? I can only answer, that the former difficulty will recur, unless it be found that