As Professor Heisenberg, in his lecture quoted earlier (Chapter II), rightly remarks, Goethe strove directly with Newton only in the realms of colour-theory and optics. Nevertheless his campaign was not merely against Newton's opinions in this field. He was guided throughout by the conviction that the fundamental principles of the whole Newtonian outlook were at stake. It was for this reason that his polemics against Newton were so strongly expressed, although he had no fondness for such controversies. In looking back on that part of the Farbenlehre which he had himself called 'Polemical' in the title, he said to Eckermann: 'I by no means disavow my severe dissections of the Newtonian statements; it was necessary at the time and will also have its value hereafter; but at bottom all polemical action is repugnant to my nature, and I can take but little pleasure in it.'