7. It would be a great mistake to judge all the inhabitants of a city by those who inhabit the lowest and most sordid places. In a hospital we see none but the sick and mutilated; in a prison we find gathered together all kinds of vileness, baseness and many vices; in unhealthy regions the inhabitants are, for the most part, pale, puny and sickly. Well then, picture the Earth as a combination of a suburb, a hospital, and an unhealthy place, because it is all of these put together. Then it can be understood why afflictions outweigh pleasures, for we do not send those who are healthy to hospital, nor do we throw those who have practised no wrong into houses of correction; neither can hospitals and houses of correction be places of delight.
So in the same way that the total population of a city is not to be found in us hospitals and prisons, we do not find the total population of humanity here on Earth. Just as the sick leave hospital when they are cured and those who have served their term leave prison, when Man is cured of all his moral infirmities he will also leave the Earth environment to go to happier worlds.