Nobel lecture december 12, 1933 On passing through an optical instrument, such as a telescope or a camera lens, a ray of light is subjec reflecting surface. The path of the rays can be constructed if we know the two simple laws which govern the changes in direction: the law of refrac- tion which was discovered by Snellius a few hundred years ago, and the law of reflection with which Archimedes was familiar more than 2,000 years ago