Harper left Frenchton to pursue his dream by attending the Art Academy of Cincinnati. On his first day there, he met his future wife, Edie McKee. WWII interrupted his studies in December 1942, taking him to the European campaign, serving as a scout on the front lines. Upon his return in 1945, he enrolled at the Art Students League in New York, but he found the frenzy of Manhattan overwhelming and returned to Cincinnati to finish out his education. Harper learned to paint realistically. He found however that this was limiting and that this method of dealing with form "revealed nothing about the subject that nature hadn't done better. It would never allow me the freedom to editorialize visually and respond emotionally to the subject.
Gradually, I came to feel that the picture plane should be affirmed and preserved, not denied and obliterated. Now I avoid linear perspective which penetrates the plane, because they are transitory, constantly shifting and have nothing to do with the true form of an object, which exists unchanged by either the presence or absence of light." He added, "I believe every artist should learn how to paint realistically regardless of the path he chooses later. You must learn to put everything in before you will know what can be left out successfully. You must control nature before you can distort it."