Prisms have been used for hundreds of years to study the properties and composition of light. Near the beginning of the Enlightenment, Isaac Newton used equilateral prisms to conduct some of the most famous of these experiments. At the time of his work, it was commonly known that white light entering prisms would appear to become multi-colored as it passed through and exited the glass. However, many people believed that this occurred because the prism itself was “polluting” or coloring the light. Through careful experimentation and the use of several prisms, Newton was able to demonstrate that this effect actually existed because white light was actually a mixture of several distinct colors that were separated by the prism.