If we look at the sky and see the naturally formed pictures made by the clouds floating about and grouping differently, we can easily understand the nature of form, seeing how an elephant formed in the clouds turns suddenly into a horse, and how from a horse changes into the form of a camel or of some human being, or into the form of a bird or beast. It is nothing, but the grouping and the scattering of the atoms of the clouds, and the proportion of light or shade falling on them helps to distinguish forms.