Arthur Hacker is high-key - luminous, open, and weighted toward light. Arthur Hacker builds on cool foundations: the palette favours the blue-cyan-green arc. Chroma is kept low across all colours, producing the soft, enveloping quality that characterises tonal painting. The most saturated colour, #412515, is reserved to 3.5% of the surface, where it acts as a focal punctuation. 70 units of value range underpin the palette's structural clarity: the eye always knows where light falls. High luminosity and cool temperature suggest the plein-air condition: unfiltered daylight and open sky. In the context of Arthur Hacker's full range of palettes, group 1 represents one movement in an ongoing chromatic dialogue.