Christopher Whall,
Stained Glass Work: A text-book for students and workers in glass
“ When, therefore, the main relations of colour have been all set out and decided for your window, turn your attention to small differences, to harmonies round the harmonies. Make each note into a chord, each tint into a group of tints, not only the strong and bold, but also the subtle and tender; do not miss the value of small modifications of tint that soften brilliance into glow. Study how Nature does it on the petals of the pansy or sweet-pea. You think a pansy is purple, and there an end? ”
