Isaac Newton was the first to make a systematic study of color. He did this by passing a narrow beam of sunlight through a triangular-shaped glass prism. His method showed that sunlight is composed of a mixture of all the colors of the rainbow. In a rainbow or the separation of colors by a prism we see the continuous range of spectral colors (the visible spectrum). The spectrum is often divided up into named colors, though any division is somewhat arbitrary: the spectrum is continuous. Traditional colors include: red, orange, yellow, green, blue, and violet.