Yet nature makes use of number as a regulating factor in quite a different way from its appearance in the purely electrical and gravitational connexions of inorganic matter, namely where sound-ether from the upper boundary of nature so regulates nature's dynamic that the manifold sense-qualities appear in their time-and-space order. When we interpret the arrangement of numbers found there on a nominalistic basis, as is done when the axis- and angle-relationships of crystals are reduced to a mere propinquity of the atoms distributed like a grid in space, or when the difference in angle of the position of the various colours in the spectrum is reduced to mere differences in frequency of the electromagnetic oscillations in a hypothetical ether - then we bar the way to the comprehension not only of number itself, as a quality among qualities, but also of all other qualities in nature.