ROGER BACON'S DE SENSU COLOUR THEORY

The paper reconstructs Roger Bacon's theory of colour as presented in his questions on Aristotle's On Sense and Sensibilia. It argues that according to Bacon real colours do not depend on light but are rather properties of a mixture made up of the elements. Bacon held to the position that trans-parency and determinate limits are not necessary conditions of being coloured and asserted that light has a significant function in the being of apparent colours, but not in the being and essence of real colours. More-over, he declared that colours have complete actuality, in light as in dark-ness, and that their inherent visibility is independent of light. Accordingly, he rejected Grosseteste' theory of colour as light embodied in transparency. This renders Bacon an extreme realist concerning the ontological status of colour. In his mature writings, such as the Opus majus, Bacon still held to the same extreme realist position concerning colour. He developed further the distinction between real and apparent colours, taking the theory he laid down in his questions on De sensu as premise.