Isaac Newton was an English scientist, astronomer, and mathematician. He is considered by many to be the greatest scientist of all time. Even the great Albert Einstein believed that Newton "deserves our deep veneration." There were many things in the universe that fascinated Newton-especially light and motion. Using a prism, Newton first discovered that sunlight is made up of light rays of many different colors. Today, scientists work out complex ideas using calculus, the branch of mathematics developed by Newton. But Newton is best known for his theories of motion and gravitation. These laws have guided scientists for three hundred years.