Here is repeated in a special way the threefold organization of man, for the seeing of colour depends on an organic process apart from the nerve processes and similar to that which takes place between heart and lungs, whilst the seeing of forms and spatial vision depend upon certain movements of the eyeball (quick traversing of the outline of the viewed object with the line of sight, alteration of the angle between the two axes of sight according to distance), in which the eye is active as a sort of outer limb of the body, an activity which enters our consciousness as little as does that of our limbs. It now becomes clear that no world-content obtained in such more or less unconscious ways could be made available for the building of a new scientific world-conception. Only as much as man experiences through the sight of a single, colour-blind eye, could be used.⁹