Rule Golden and Other Stories - Damon Knight

Another excellent collection of SFWA Grandmaster Damon Knight's always-excellent stories--five novellas in this case, generally circling around "the great unsolved problem of politics: how to keep the bastards from grinding you down."
Rule Golden--what if the Golden Rule were enforced in reverse by some force--the bad things you do to others are done to you?
Natural State--are cities doomed by genetic engineering?
Double Meaning--a race against time to find a shape-shifting alien spy.
The Earth Quarter--why did the aliens on a remote planet keep all the humans locked inside a section of the city?
The Dying Man--what would it be like to be immortal... then suddenly find out you'd become mortal?