George Wald (1906-1997) was awarded one-third of the 1967 Nobel Prize in Physiology or Medicine for his discoveries concerning the primary physiological and chemical visual processes in the eye. Wald discovered that vitamin A is a vital ingredient of the pigments in the retina and is important in maintaining vision. Later, he elucidated the chemical reactions involved in the vision process of the eye’s rod cells. With Paul K. Brown, he identified the pigments in the retina that are sensitive to yellow-green, red, and blue light. Wald and Brown also discovered the role of vitamin A in forming the three color pigments and showed that color blindness is caused by the absence of one of them.