And deep drinks The mighty bow, when rain is brewing. But the threat the bow conveys is not the same whatever the quarter it has shown itself in. If it rises toward the 2 south, it will bring a heavy fall. The rain in that quarter, such is its force, cannot be mastered by the strongest midday sun. If it shine toward the west, there will be only a dew or a light rain. If it rise in the east or thereabouts, it prognosticates fine weather. If, however, the bow is the sun’s reflection, why does it appear of far larger size than the sun himself? Just because there is a kind of mirror that exhibits objects on a far larger scale than that on which they are presented to it, increasing their form to a portentous magnitude: and in turn there is another kind that reduces the size. And tell me this again, why does an image assume the form of a circle if it does not answer to a circle? You may, perhaps, tell me why the colour 3 of the bow is varied: why its shape is what it is, you will not be able to tell me except by citing some model after which it is formed. Now, other model there is none save that of the sun; when you admit that the rainbow receives its colour from him, it follows that it receives its shape also from him. In short, you and I are agreed that those colours by which its quarter of the heaven is adorned proceed from the sun. But on one point we are not agreed: you say that the colour is real; I maintain that it is only apparent. Whichever it is, real or apparent, it comes from the sun. On your assumption its sudden cessation cannot be explained, seeing that all other bright lights in the sky are dispelled gradually. Its sudden appearance and, at the same time, its 4 sudden extinction make for my contention. For it is a peculiarity of a mirror that the reflection in it is not built up piecemeal, but all at once comes fully into being. Every image in it is destroyed, too, with as great rapidity as it was formed. For to the construction or removal of the images nothing is required but the presentation and withdrawal of the objects.