Nabokov believed in details. He believed the smallest things mattered most when attempting to uncover the larger picture, and he applied this not only to literature — with his careful examination of words, descriptions, and fictional space — but also to lepidoptery — with his rejection of genetics as an accurate way to distinguish butterfly species (he preferred the traditional method of carefully examining their genitalia under a microscope, often for hours a day).
While working as a professor at Cornell, Nabokov once asked his students to name the color of the wallpaper in a fictional character's bedroom, a detail mentioned only once in the novel they were reading. (Such a question, I imagine, forced his students to read in ways they previously had not — especially since he asked it on an exam!) Applying this detail-oriented approach to The Metamorphosis allowed Nabokov to confidently determine what sort of "gigantic" (Nabokov preferred "monstrous") insect Gregor Samsa had become. Some people had said he was a cockroach, but Nabokov pointed out that cockroaches are flat and have large legs, while Gregor was "convex on both sides" with small legs. "He approaches a cockroach in only one respect: his coloration is brown. That is all." Nabokov concluded with certainty that Gregor Samsa must be a beetle, but what did this yield? Well, Gregor never realized he had wings! Nabokov: "This is a very nice observation on my part to be treasured all your lives. Some Gregors, some Joes and Janes, do not know that they have wings."