The protagonist of these neo-Herbartians was Robert Zimmermann. He constructed his system of Aesthetic out of Herbart, whom he perverted to his own uses, and even employed the much-abused Hegelian dialectic in order to introduce modifications of the beautiful into pure beauty. The beautiful, he said, is a model which possesses greatness, fulness, order, correction, and definite compensation. Beauty appears to us in a characteristic form, as a copy of this model.
Vischer, against whom was directed this work of Zimmermann, found it easy to reply. He ridiculed Zimmermann's meaning of the symbol as the object around which are clustered beautiful forms. "Does an artist paint a fox, simply that he may depict an object of animal nature. No, no, my dear sir, far from it. This fox is a symbol, because the painter here employs lines and colours, in order to express something different from lines and colours. 'You think I am a fox,' cries the painted animal. 'You are mightily mistaken; I am, on the contrary, a portmanteau, an exhibition by the painter of red, white, grey, and yellow tints.'" Vischer also made fun of Zimmermann's enthusiasm for the aesthetic value of the sense of touch. "What joy it must be to touch the back of the bust of Hercules in repose! To stroke the sinuous limbs of the Venus of Milo or of the Faun of Barberini must give a pleasure to the hand equal to that of the ear as it listens to the puissant fugues of Bach or to the suave melodies of Mozart." Vischer defined the formal Aesthetic of Zimmermann as a queer mixture of mysticism and mathematic.
Lotze, in common with the great majority of thinkers, was dissatisfied with Zimmermann, but could only oppose his formalism with a variety of the old mystical Aesthetic. Who, he asked, could believe that the human form pleases only by its external proportions, regardless of the spirit within. Art, like beauty, should "enclose the world of values in the world of forms." This struggle between the Aesthetic of the content and the Aesthetic of the form attained its greatest height in Germany between 1860 and 1870, with Zimmermann, Vischer, and Lotze as protagonists.
These writers were followed by J. Schmidt, who in 1875 ventured to say that both Lotze and Zimmermann had failed to see that the problem of Aesthetic concerned, not the beauty or ugliness of the content or of the form as mathematical relations, but their representation; Köstlin, who erected an immense artificial structure with the materials of his predecessors modified; Schasler, who is interesting as having converted the old Vischer to his thesis of the importance of the Ugly, as introducing modifications into the beautiful and being the principle of movement there. Vischer confesses that at one time he had followed the Hegelian method and believed that in the essence of beauty is born a disquietude, a fermentation, a struggle: the Idea conquers, hurls the image into the unlimited, and the Sublime is born; but the image, offended in its finitude, declares war upon the Idea, and the Comic appears. Thus the fight is finished and the Beautiful returns to itself, as the result of these struggles. But now, he says, Schasler has persuaded him that the Ugly is the leaven which is necessary to all the special forms of the Beautiful.