Imagine the effect where this rule of gradation or ascending scale is reversed.

A tinted floor of cream colour, or even white, and a ceiling as deep in colour as a landscape.

One feels as if they themselves were reversed, and standing upon their heads.

Certainly if we ignore this law we lose our sense of base or foundation, and although we may not know exactly why, we shall miss the restfulness of a properly constructed scheme of decoration.
The rule of gradation includes also that of massing of colour.

In all simple treatment of interiors, whatever colour is chosen should be allowed space enough to establish its influence, broadly and freely, and here again we get a lesson from nature in the massing of colour.