3 - Theoretical traditions in physical optics, 1700–45

Summary

Development of the emission tradition

Newton's suggestions

The theoretical tradition in physical optics in which light is regarded as an emission of matter goes back at least as far as Greek Antiquity and has experienced a renaissance in modern times. Newton was a major representative of the emission tradition in seventeenthcentury optics. In the Enlightenment period his ideas dominated this tradition, although he never held the position of an absolute ruler. Despite his unmistakably great importance for the eighteenth-century emission tradition, Newton had a curious status within it. He never unreservedly endorsed the emission hypothesis, in print at any rate. This is connected with his approach to methodology: He attempted to abstain from combining certainties with doubts. Consequently Newton's ideas on the emission of light are mainly encountered in the form of queries forming a supplement to his Opticks. His ideas remained suggestions that were unconnected with one another, provided no solution to some problems, and were occasionally inconsistent. In addition, they changed over time. For this reason we need a detailed study of the different versions of the ‘queries’ in the various editions of the Opticks if we are to obtain a clear and accurate account of Newton's ideas on the nature of light and of the later attempts to systematize his suggestions. The first edition (Opticks, 1704), the first Latin edition (Optice, 1706), and the second English edition of 1717, are the most important for our purposes.