Featured on PDR in the collection Edwin D. Babbitt’s Principles of Light and Color (1878)

While chromotherapy — the correction of physical and psychic imbalances through exposure to antidotal hues — is now widely dismissed as pseudoscience, its influence is everywhere in our LED-lit world. If you’ve ever worn blue light–blocking glasses, made your smartphone screen grayscale to lessen its addictive pull, dabbled with “Seasonal Color Analysis” (a system to match clothing to complexion), or gazed into a full-spectrum SAD lamp to cure the winter blues, you have engaged with the legacy of a notably late-nineteenth-century tenet. Chromotherapy bundled religious instincts with feel-good optical optimism. Stained glass no longer merely symbolized the sacred. It became a portal to the promise of renewed life through science.