This problem is the most difficult and at the same time the one that mankind solves last.
The difficulty, which even the mere idea of this task clearly reveals, is the following: man is an animal who, if he lives among others of his kind, needs a master, for man certainly misuses his freedom in regard to others of his kind and, even though as a rational being he desires a law that would provide limits for the freedom of all, his egoistic animal inclination misguides him into excluding himself where he can. Man therefore needs a master who can break man's will and compel him to obey a general will under which every man could be free. But where is he to get this master? Nowhere else but from mankind. But then this master is in turn an animal who needs a master. Therefore one cannot see how man, try as he will, could secure a master charged with maintaining public justice who would be himself just. This is true whether one seeks to discover such a master in a single person or in a group of elected persons. For each of these will always abuse his freedom if he has no one over him who wields power according to the laws. Yet the highest master is supposed to be just in himself and yet a man. The task involved is therefore most difficult; indeed, a complete solution is impossible. One cannot fashion something absolutely straight from wood that is as crooked as that of which man is made. Nature has imposed upon us the task of approximating this idea. That his task should be the latest that man achieves follows from yet another consideration: the right conceptions regarding the nature of a possible constitution. Great experience in many activities and a good will that is prepared to accept such a constitution are all required. Obviously it will be very difficult, and if it happens it will be very late and after many unsuccessful attempts that three such things are found together.