Signs and sign interpretation

Abstract

In 1671, in a letter to the Royal Society for the Improvement of Knowledge, Newton gave a first account of his theory of colors based on the prism experiments he started in 1665. Notably, it was not the colors that drew Newton’s special attention. The refractory potential of glass prisms was commonly known at that time. He was struck by the oblong form and the specific order of colors in the spectrum (Sabra, 1981). In his ‘experimentum crucis’, Newton showed that those light rays are primary in a twofold way. First, by merging them in a single bundle, white light arises again, and second, leading the separate color rays through a second prism does not lead to further refraction. Newton writes (Newton, 1959/1671): “Light it self is a Heterogeneous mixture of refrangible Rays”. Elsewhere he writes: “[Colors are] original and connate properties of the rays just as their respective degrees of refrangibility were”