It is this state, which was reached only after a long period, not the original state of nature, that Rousseau considers to have been the happiest period of the human race.

This period of the development of human faculties, holding a just mean between the indolence of the primitive state and the petulant activity of our self-love, must be the happiest and most durable epoch.  The more we reflect on it, the more we find that this state was the least exposed to revolutions and the best for man; and that he can have left it only through some fatal chance which, for the common advantage, should never have occurred.  The example of the savages who have almost all been found in this state seems to bear out the conclusion that humanity was made to remain in it for ever, that it was the true youth of the world, and that all further progresses have been so many steps, apparently towards the perfection of the individual, and really towards the decrepitude of the species.

He ascribes to metallurgy and agriculture the fatal resolution which brought this Arcadian existence to an end.  Agriculture entailed the origin of property in land.  Moral and social inequality were introduced by the man who first enclosed a piece of land and said, This is mine, and found people simple enough to believe him.  He was the founder of civil society.

The general argument amounts to this:  Man’s faculty of improving himself is the source of his other faculties, including his sociability, and has been fatal to his happiness.  The circumstances of his primeval life favoured the growth of this faculty, and in making man sociable they made him wicked; they developed the reason of the individual and thereby caused the species to deteriorate.  If the process had stopped at a certain point, all would have been well; but man’s capacities, stimulated by fortuitous circumstances, urged him onward, and leaving behind him the peaceful Arcadia where he should have remained safe and content, he set out on the fatal road which led to the calamities of civilisation.  We need not follow Rousseau in his description of those calamities which he attributes to wealth and the artificial conditions of society.  His indictment was too general and rhetorical to make much impression.  In truth, a more powerful and comprehensive case against civilised society was drawn up about the same time, though with a very different motive, by one whose thought represented all that was opposed to Rousseau’s teaching.  Burke’s early work, A Vindication of Natural Society, [Footnote:  A.D. 1756.] was written to show that all the objections which Deists like Bolingbroke urged against artificial religion could be brought with greater force against artificial society, and he worked out in detail a historical picture of the evils of civilisation which is far more telling than Rousseau’s generalities. [Footnote:  In his admirable edition of The Political Writings of Jean-Jacques Rousseau (1915), p. 89, Vaughan suggests that in Rousseau’s later works we may possibly detect “the first faint beginnings” of a belief in Progress, and attributes this to the influence of Montesquieu.]