Already, indeed, the picture of nature which we gained from following Goethe's studies both of the plant and of meteorological happenings has brought us face to face with certain aspects of levity. For when Goethe speaks of systole and diastole, as the plant first taught him to see them and as later he found them forming the basic factors of weather-formation, he is really speaking of the ancient concepts, 'cold' and 'warm'. Goethe's way of observing nature is, in fact, a first step beyond the limits of a science which kept itself ignorant of levity as a cosmic counterpart to terrestrial gravity. To recognize the historical significance of this step, let us turn our glance to the moment when the human mind became aware that to lay a proper foundation for the science it was about to build, it had to exclude any idea of levity as something with a real existence. Many a conception which is taken for granted by modern man, and is therefore assumed to have been always obvious, was in fact established quite deliberately at a definite historical moment. We have seen how this applies to our knowledge of the gaseous state of matter; it applies also to the idea of the uniqueness of gravity. About half a century after van Helmont's discovery a treatise called Contra Levitatem was published in Florence by the Accademia del Cimento. It declares that a science firmly based on observation has no right to speak of Levity as something claiming equal rank with, and opposite to, Gravity. This attitude was in accord with the state into which human consciousness had entered at that time. For a consciousness which is itself of the quality 'cold', because it is based on the contracting forces of the body, is naturally not in a position to take into consideration its very opposite. Therefore, to speak of a force of levity as one felt able to speak of gravity was indeed without meaning. Just as there was historical necessity in this banishing of levity from science at the beginning of the age of the spectator-consciousness, so was there historical necessity in a renewed awareness of it arising when the time came for man to overcome the limitations of his spectator - relationship to the world. We find this in Goethe's impulse to search for the action of polarities in nature. As we shall see later, it comes to its clearest expression in Goethe's optical conceptions. Another witness to this fact is Ruskin, through a remark which bears in more than one sense on our present subject. It occurs in his essay, The Storm-Cloud of the Ninteenth Century. In its context it is meant to warn the reader against treating science, which Ruskin praises as a fact-finding instrument, as an interpreter of natural facts. Ruskin takes Newton's conception of gravity as the all-moving cause of the universe, and turns against it in the following words: