Abstract

Light is strangely absent from most accounts of the environment. From photosynthesis to vitamin D, however, light is central to human well-being. Human circadian rhythms are keyed the alternation of dark and light. Erosion of the ozone layer makes skin cancer a growing threat from excess ultraviolet radiation. Light plays a significant role in health and illness. In changing historical circumstances, light continues to evoke and to express significant issues of value.