Enlightenment

He also reported to curing certain diseases and increasing fertility, as well as increasing the rate of physical maturation in animals by exposing them to blue light. Pleasanton maintained that blue light was also effective in treating human diseases and pain. His work gained supporters, but was dismissed by the medical establishment as unscientific.

With the advent of physical medicine and treatments such as surgery and antiseptics, interest in healing with colour declined. It did not resurface until the nineteenth century, and then not in Europe but North America. In 1876 Augustus Pleasanton published his findings on the effects of colour in plants, animals and humans. He claimed that the quality, yield and size of grapes could be significantly increased if they were grown in glasshouses with alternating blue and transparent panes.