 Siegel objected to any proposal that Lois discover that Clark is Superman because he felt that, as implausible as Clark's disguise is, the love triangle was too important to the book's appeal.However, Siegel wrote stories in which Lois suspects Clark is Superman and tries to prove it, with Superman always duping her in the end; the first such story was in "Superman" #17 (July–August 1942).This was common plot in comic book stories prior to the 1970s.