It seems almost a truism to say that colour is a sensation; and yet Young, by honestly recognizing this elementary truth, established the first consistent theory of colour. So far as I know, Thomas Young was the first who, starting from the well-known fact that there are three primary colours, sought for the explanation of this fact, not in the nature of light, but in the constitution of man. (James Clerk Maxwell, p. 267.)It is doubtless scientific to disregard certain aspects (...) when we work; but to urge that therefore such aspects are not fact, and that what we use without them is an independent real thing-this is barbarous metaphysics. (F. H. Bradley, p. 15.). (shrink)