Trurl the constructor whose inventions tend to make life complicated for anyone in the vicinity and his cohort Klapaucius make their welcome appearance in this attractive collection by Polish SF writer Lem (translated by Michael Kandel). Asking the machine that can do everything to do nothing almost destroys the universe and a more benevolent creation wipes out war or at least one battle; and there are various other wonders worth pondering. The intelligent, ironic Lem is a real find.