The text surveys traditional and esoteric meanings attached to colours, arguing that hues function as symbols and vibratory forces linked to emotion, music, and the natural world. It treats individual colours in turn—red, yellow, green, blue, purple, white, black, brown and grey—and considers the rainbow, tracing cultural lore, gem and talismanic uses, and artistic and poetic responses. Practical topics include medical and agricultural applications of coloured rays, meteorological colour signs, chromatics of the sky, and the proposed correspondence between colour and sound. Appendices outline schools of colour, planetary colours, and experiments on plant growth under coloured light.