THE ANALOGY OF COLOURS, &c. 143 CHAPTER III. CHROMATICS. SECTION I. 1034. THE term CHROMATICS denotes herein the science of the relations of Light, Shade, and Colour, as the preceding science, Plastics, does the parallel relations of Position, Magnitude, and Figure; and as the following science, Harmonics, does Acuteness, Gravity, and Harmonious sounds, or Sound, Silence, and Note. 1035. As Figure belongs to the sense of feeling or touch immediately, and Note to the sense of sound, so Light, Shade, and Colours belong to the eye, or visual sense; for, notwithstanding figure, number, and motion become objects of vision, they do so only by the agency of light, shade, and colours, which are the sole immediate and peculiar objects of sight and Chromatic science; and are sensible representations of material objects to the mind. 1036. Light and Shade are the Agent and Patient, or generating principles, or elements of all visual effects, and are, therefore, correlative, coessential, and concurrent; accordingly, the light of day, and the sunbeam itself, are compounds of light and shade, nor are pure light or pure shade in any case objects of vision. 1037. Concurrent light and shade are either Achromatic, or colourless, or they are Chromatic, or coloured. Light, Shade, and Colours are, also, either inherent, as in pigments, &c., or transient, as in the sunbeam, rainbow, prismatic spectra, &c. The first arising from reflection, the latter from refraction, &c. 1038. Inherent light and shade are called white and black, but in the transient state light and shade are denominated light and dark. 1039. It follows from the above that the principles of light and shade have three states or modes of concurrence, which are convertible; one sensible, as above; another latent, as in colours; and a third conjunctive, in which the sensible and latent are united: thus, for example, these principles are coessential, and concurrent latently in the colours of pigments, &c., which also variously participate of these powers sensibly in the variety of their depth and brilliancy. 1040. The principles of light and shade in their sensible state have two extremes and a mean, which, when inherent, are denominated white, |