Short stories by science fiction authors about the role of the hard sciences in particular science fiction stories they have written. Essays by Heinlein (And He built a Crooked House), Leinster (Wabbler), Thomas (Weather Man), Silverberg (Artifact Business), Schmitz (Grandpa), Asimov (Not Final), Kornbluth (Little Black Bag), Latham (Blindness), Clarke (Take a Deep Breath), Vance (Potters of Firsk), Huxley (Tissue-Culture King).