They may be his most famous, but Andy Warhol‘s “Sex Parts” series were not the artist’s first nudes. The originals date all the way back to Warhol’s days as a commercial illustrator, when, in between working on shoe ads and album covers, he’d also occasionally turn his attention to line drawings, using a ballpoint pen to sketch out the delicate outlines of, more often than not, either a face or a penis. In some ways, those illustrations are even racier than their famed counterparts: Whereas the latter rely on vivid colors to catch the eye, the stark lines of the former have such playful confidence that it’s hard to believe he only dared to incorporate nudity into his fine art practice two decades later—and even then, only in private. (They weren’t even exhibited in Warhol’s lifetime.) These days, of course, the idea that a gallery would be too fearful to exhibit Warholian phalluses is almost laughable, and there’s definitely no shortage of them at the moment in New York City, in the Whitney Museum and beyond. On view through March 10, a new exhibition at the New York Academy of Art showcases Warhol’s draftsmanship—and to say that it’s comprehensive may be an understatement: The 150-plus drawings on view, some for the first time ever in the U.S., stretch from 1948, when Warhol was a 20-year-old, to 1985, two years before his death. Take a look inside—and at yet another side of Warhol—here.