“I am a Rorschach test,” Hillary Clinton told Esquire magazine in 1993. The label stuck — everything from her campaign to her “no-makeup face” has been described similarly. She’s not the only one.

Just after April Fools’ Day in 1922, Hermann Rorschach, a psychologist who used a collection of symmetrical inkblots to treat patients with manic depression and schizophrenia, died of appendicitis in ...