Furthermore, we would encourage the artist to gain knowledge also of the inorganic world; this can be done all the more easily since now we can conveniently and quickly acquire knowledge of the mineral kingdom. The painter needs some knowledge of stones in order to imitate their characteristics; the sculptor and architect, in order to utilize them; the cutter of precious stones cannot be without a knowledge of their nature; the connoisseur and amateur, too, will strive for such information.

Now that we have advised the artist to gain a conception of the general operations of Nature, in order to become acquainted with those which particularly interest him, partly to develop himself in more directions, partly to understand better that which concerns him; we shall add a few further remarks on this significant point.

Up to the present the painter has been able merely to wonder at the physicist's theory of colors, without gaining any advantage from it. The natural feeling of the artist, however, constant training, and a practical necessity led him into a way of his own. He felt the vivid contrasts out of the union of which harmony of color arises, he designated certain characteristics through approximate sensations, he had warm and cold colors, colors which express proximity, others which express distance, and what not; and thus in his own way he brought these phenomena closer to the most general laws of Nature. Perhaps the supposition is confirmed that the operations of Nature in colors, as well as magnetic, electric, and other operations, depend upon a mutual relation, a polarity, or whatever else we might call the twofold or manifold aspects of a distinct unity.

We shall make it our duty to present this matter in detail and in a form comprehensible to the artist; and we can be the more hopeful of doing something welcome to him, since we shall be concerned only with explaining and tracing to fundamental principles things which he has hitherto done by instinct.

So much for what we hope to impart in regard to Nature; now for what is most necessary in regard to Art.

Since the arrangement of this work proposes the presentation of single treatises, some of these only in part, and since it is not our desire to dissect a whole, but rather to build up a whole from many parts, it will be necessary to present, as soon as possible and in a general summary, those thing's which the reader will gradually find unfolded in our detailed elaborations. We shall, therefore, be occupied first with an essay on plastic art, in which the familiar rubrics will be presented according to our interpretation and method. Here it will be our main concern to emphasize the importance of every branch of Art, and to show that the artist must not neglect a single one, as has unfortunately often happened, and still happens.

Hitherto we have regarded Nature as the treasure chamber of material in general; now, however, we reach the important point where it is shown how Art prepares its materials for itself.

When the artist takes any object of Nature, the object no longer belongs to Nature; indeed, we can say that the artist creates the object in that moment, by extracting from it all that is significant, characteristic, interesting, or rather by putting into it a higher value. In this way finer proportions, nobler forms, higher characteristics are, as it were, forced upon the human figure; the circle of regularity, perfection, signification, and completeness is drawn, in which Nature gladly places her best possessions even though elsewhere in her vast extent she easily degenerates into ugliness and loses herself in indifference.

The same is true of composite works of art, of their subject and content, whether the theme be fable or history. Happy the artist who makes no mistake in undertaking the work, who knows how to choose, or rather to determine what is suitable for art! He who wanders uneasily among scattered myths and far-stretching history in search of a theme, he who wishes to be significantly scholarly or allegorically interesting, will often be checked in the midst of his work by unexpected obstacles, or will miss his finest aim after the completion of the work. He who does not speak clearly to the senses, will not address himself clearly to the mind; and we regard this point as so important that we insert at the very outset a more extended discussion of it.

A theme having been happily found or invented, it is subjected to treatment which we would divide into the spiritual the sensuous, and the mechanical. The spiritual develops the subject according to its inner relations, it discovers subordinate motives; and, if we can at all judge the depth of ar artistic genius by the choice of subject, we can recognize in his selection of themes his breadth, wealth, fullness, and power of attraction. The sensuous treatment we should define as that through which the work becomes thoroughly comprehensible to the senses, agreeable, delightful, and irresistible through its gentle charm. The mechanical treatment, finally, is that which works upon given material through any bodily organ, and thus brings the work into existence and gives it reality.