Understanding the percepts elicited by spectral distributions in visual stimuli (i.e. understanding the perception of colour) is made especially challenging by the peculiar phenomenology of colour contrast and constancy effects. Interestingly as the first systematic account of colour contrast was published in 1839 by the French chemist Michel Chevreul based on work done while serving as the director of dyes for the Royal Manufacturers. In this current paper we review the nature of colour vision, the problems that the observations of Chevreul and others present for colour science, and recent work that suggests a solution. © Rev. Prog. Color.