If a single tint is to be used, the walls must take the next gradation, and the ceiling the last.

These gradations must be far enough removed from each other in depth of tone to be quite apparent, but not to lose their relation.

The connecting grades may appear in furniture covering and draperies, thus giving different values in the same tone, the relation between them being perfectly apparent.

These three masses of related colour are the groundwork upon which one can play infinite variations, and is really the same law upon which a picture is composed.

There are foreground, middle-distance, and sky--and in a properly coloured room, the floors, walls, and ceiling bear the same relation to each other as the grades of colour in a picture, or in a landscape.
Fortunately we keep to this law almost by instinct, and yet I have seen a white-carpeted floor in a room with a painted ceiling of considerable depth of colour.