Whatever type of metamorphosis is followed by a plant (and there are others as well, so that we may even speak of metamorphoses between different types of metamorphosis!) they all obey the same basic rule, namely, that before proceeding to the next higher stage of the cycle, the plant sacrifices something already achieved in a preceding one. Behind the inconspicuous sheath of the calyx we see the plant preparing itself for a new creation of an entirely different order. As successor to the leaf, the flower appears to us time and again as a miracle. Nothing in the lower realm of the plant predicts the form, colour, scent and all the other properties of the new organ produced at this stage. The completed leaf, preceding the plant's withdrawal into the calyx, represents a triumph of structure over matter. Now, in the flower, matter is overcome to a still higher degree. It is as if the material substance here becomes transparent, so that what is immaterial in the plant may shine through its outer surface.