Twenty-odd years before Newton stated the three laws of motion, he conducted a simple, breakthrough prism experiment. He poked a hole through his window shade, allowing a single beam of light to shine through. Placing a prism in the light’s path, he broke the beam into its color spectrum. If light were composed of a rainbow of colors, he reasoned, he should be able to recombine them into white sunlight by passing them through a lens and a second prism. He was right.