The reason why Goethe chose optics as the field of conflict, and devoted to it more than twenty years of research and reflexion, amidst all the other labours of his rich life, lay certainly in his individual temperament – ‘zum Sehen geboren, zum Schauen bestellt‘.¹ At the same time one must see here a definite guidance of humanity. Since the hour had struck for mankind to take the first step towards overcoming the world-conception of the one-eyed, colour-blind onlooker, what step could have been more appropriate than this of Goethe’s, when he raised the eye’s capacity for seeing colours to the rank of an instrument of scientific cognition?