Color theory — the association of certain colors with patterns of emotions — has recently become an area of significant scholarly research. Operatic lighting designers, however, have been intuitively using lighting to illuminate and emphasize emotional resonances for decades now. “If you’ve got a key change, it’s time to get color involved,” says Duane Schuler, a lighting specialist who has worked with the Metropolitan Opera, Lyric Opera of Chicago, and more. Schuler lit a production for LA Opera that the company revived in November 2022: “You might want reds and ambers for major keys; blues and greens and purples for minor keys. When Scarpia makes his first entrance in Tosca, in the middle of the children’s chorus, the whole mood changes.