Low-key values are the structural spine of Gustave Courbet, giving it gravity and atmosphere. Temperature is cool-dominant, with blue and green families claiming the largest areas. The absence of saturated colour is itself an expressive choice: this is a palette of restraint and atmosphere. #23221C claims 28.0% of the surface, functioning as the work's tonal foundation. Only 4.2% is devoted to #624932, yet that small allocation delivers the palette's entire chromatic tension. The value range of 52 units sits in the comfortable middle: enough depth, enough light, neither extreme. The combination of low values, muted chroma, and compressed range is the signature of the Tonalist mode - painting as atmosphere. In the context of Gustave Courbet's full range of palettes, group 17 represents one movement in an ongoing chromatic dialogue.