Other than that, finding Lest Darkness Fall all those years ago didn't change my life at all.

De Camp had no small effect on the fields of science fiction and fantasy, either. Working alone and in collaboration with Fletcher Pratt, he helped expand the fields by using their techniques to examine not just the present and future but also the past, and by using modern viewpoint characters to get inside works of literature written from a very different perspective. Along with Lest Darkness Fall, the Harold Shea stories collected in book form as The Incomplete Enchanter, The Castle of Iron, and Wall of Serpents have been in print almost continuously for the past sixty years.

Sprague's special virtues were logic, clarity, and a sympathetic understanding for the foibles of mankind. The heroes he created himself were always recognizably human and flawed, much more likely to try to work their way out of trouble with a quip and a smile than by smashing through whatever was in their way. (I am conscious of the irony of Sprague's having been a major factor in the rediscovery of Robert E. Howard's Conan, and in his often working in Howard's universe. Everyone's entitled to a little time off from what he usually does, and writers have to pay their bills no less than any other mortals?and I don't think anyone but Howard ever wrote Conan so well.) His own special science-fiction universe was that of the Viagens Interplanetarias ("Interplanetary Voyages" in Portuguese?Brazil is the leading country in this universe), which includes Rogue Queen (among other things, a splendid satire on Marxism), the stories collected in The Continent Makers, and many novels set on the low-tech world Krishna, which offers both science and swashbuckling a chance. Sprague did not believe faster-than-light travel was possible, and so did not include it in this universe; the Lorenz-Fitzgerald contractions play a role in more than one story.