Albrecht Dürer, Melencolia I (1514)

“In medieval philosophy, each individual was thought to be dominated by one of the four humors; melancholy, associated with black gall, was the least desirable of the four…An influential treatise, De occulta philosophia of Cornelius Agrippa of Nettesheim, almost certainly known to Dürer, probably holds the explanation for the number I in the title: creativity in the arts was the realm of the imagination, considered the first and lowest in the hierarchy of the three categories of genius. The next was the realm of reason, and the highest the realm of the spirit.”

–from the website of the Metropolitan Museum of Art, which you can read her