Now it will be noticed that nearly all these emotional elements of design are connected with essential conditions of our physical existence: rhythm appeals to all the sensations which accompany muscular activity; mass to all the infinite adaptations to the force of gravity which we are forced to make; the spatial judgment is equally profound and universal in its application to life; our feeling about inclined planes is connected with our necessary judgments about the conformation of the earth itself; light, again, is so necessary a condition of our existence that we become intensely sensitive to changes in its intensity. Colour is the only one of our elements which is not of critical or universal importance to life, and its emotional effect is neither so deep nor so clearly determined as the others. It will be seen, then, that the graphic arts arouse emotions in us by playing upon what one may call the overtones of some of our primary physical needs. They have, indeed, this great advantage over poetry, that they can appeal more directly and immediately to the emotional accompaniments of our bare physical existence.
If we represent these various elements in simple diagrammatic terms, this effect upon the emotions is, it must be confessed, very weak. Rhythm of line, for instance, is incomparably weaker in its stimulus of the muscular sense than is rhythm addressed to the ear in music, and such diagrams can at best arouse only faint ghost-like echoes of emotions of differing qualities; but when these emotional elements are combined with the presentation of natural appearances, above all with the appearance of the human body, we find that this effect is indefinitely heightened.
When, for instance, we look at Michelangelo’s “Jeremiah,” and realise the irresistible momentum his movements would have, we experience powerful sentiments of reverence and awe. Or when we look at Michelangelo’s “Tondo” in the Uffizi, and find a group of figures so arranged that the planes have a sequence comparable in breadth and dignity to the mouldings of the earth mounting by clearly-felt gradations to an overtopping summit, innumerable instinctive reactions are brought into play.[3]
At this point the adversary (as Leonardi da Vinci calls him) is likely enough to retort, “You have abstracted from natural forms a number of so-called emotional elements which you yourself admit are very weak when stated with diagrammatic purity; you then put them back, with the help of Michelangelo, into the natural forms whence they were derived, and at once they have value, so that after all it appears that the natural forms contain these emotional elements ready made up for us, and all that art need do is to imitate Nature.”