This I might have done in prose; but I chose verse, and even rhyme, for two reasons. The one will appear obvious; that principles, maxims, or precepts so written, both strike the reader more strongly at first, and are more easily retained by him afterwards: the other may seem odd, but is true; I found I could express them more shortly this way than in prose itself; and nothing is more certain, than that much of the force as well as grace of arguments or instructions, depends on their conciseness. I was unable to treat this part of my subject more in detail, without becoming dry and tedious; or more poetically, without sacrificing perspicuity to ornament, without wandering from the precision, or breaking the chain of reasoning: If any man can unite all these without diminution of any of them, I freely confess he will compass a thing above my capacity. What is now published, is only to be considered as a general map of Man, marking out no more than the greater parts, their extent, their limits, and their connexion, but leaving the particular to be more fully delineated in the charts which are to follow. Consequently, these epistles in their progress (if I have health and leisure to make any progress) will be less dry, and more susceptible of poetical ornament. I am here only opening the _fountains_, and clearing the passage. To deduce the _rivers_, to follow them in their course, and to observe their effects, may be a task more agreeable. EPISTLE I. ARGUMENT OF THE NATURE AND STATE OF MAN WITH RESPECT TO THE UNIVERSE. Of man in the abstract.--