From the Just comes the Unjust, in Arrogance

"You must nevertheless bear in mind what I am about to say to you: in the seed of the city of the just, a malignant seed is hidden, in its turn: the certainty and pride of being in the right -- and of being more just than many others who call themselves more just than the just. This seed ferments in bitterness, rivalry, resentment; and the natural desire of revenge on the unjust is colored by a yearning to be in their place and to act as they do."

-- Italo Calvino, Invisible Cities, from Hidden Cities 5


This is the last city Marco Polo describes in Calvino's book, wrapping up the tour by explaining the virus that grows within what must inhabit the city: Justice. The call to order mankind makes beautiful monuments which elevate its stature and make ever more grand statements about its existence. But as Hidden Cities 4 describes, immediately before, nothing else may flower:

"The city, great cemetery of the animal kingdom, was closed, aseptic, over the final buried corpses with their last fleas and their last germs. Man had finally reestablished the order of the world which he had himself upset: no other living specieis existed to cast any doubts."