It is concluded from presented experimental and theoretical consideration that the notion of “light source” is inadequate for description of the color perception and an alternative way to define and to describe the illumination is suggested. Color constancy as phenomena of perceiving the same color of curved and homogeneously painted surfaces is considered and it is shown that surface colors can be adequately represented by 3×3 matrices. There discussed a hypothesis that the dimension of the color space (the colorimetric space) is determined by the dimension of the ordinary geometric space of the visual scene and that the number of types of cones should be considered only as an implementation parameter. A straightforward solution of the image irradiance equation based on the concept of surface color and the above description of illumination is suggested and discussed.Why is color an epiphenomenon? This question is answered in connection with the main question of what kind of vital tasks require explicitly perceived color.