ase we must simulate shadow and mystery, and this can be done
by the colour-tones of blues and greens. I use these in the plural
because the shadows of both are innumerable, and because all, except
perhaps turquoise and apple-green, are natural shadow-tints. Green and
blue can be used together or separately, according to the skill and
what is called the "colour-sense" with which they are applied.

To use them together requires not only observation of colour-occurrences
in nature but sensitiveness to the more subtle out-of-door effects,
resulting from intermingling of shadows and reflection of lights. Well
done, it is one of the most beautiful and satisfactory of achievements,
but it may easily be bad by reason of sharp contrasts, or unmodified
juxtaposition.

But a room where blue in all its shades from dark to light alone
predominates, or a room where only green is used, bright and gray tones
in contrast and variation is within the reach of most colour-loving
mortals, and as both of these tints are companionable with oak and gold,
and to be found in nearly all decoration materials, it is easy to
arrange a refined and beautiful effect in either colour.

It will require little reflection to show that a hall skilfully treated
with green or blue tints would modify the colour of sunlight, without
giving a sense of discord. It would be like passing only from sunlight
to grateful shadow, and this because in all art the actual
representation shadow-colour would be blue or green. The shadow of a
tree falling upon snow on a sunny winter day is blue. The shadow of a
sunheated rock in summer is green, and the success of either of these
schemes of decoration would be because of adherence to an actual
principle of colour, or a knowledge of the peculiar qualities of certain
colours and their proper use. It would be an intelligent application of
the medicinal or healing qualities of colour to the constitution of the
house, as skilful physicians use medicines to overcome constitutional
defects or difficulties in man.

This may be called _corrective_ treatment of a room, and may, of
course, include all the decorative devices of ornament, design and
furniture, and although it is not, strictly speaking, decoration, it
should certainly and always precede decoration.

It is sad to see an elaborate scheme of ornament based upon bad
colour-treatment, and unfortunately this not infrequently happens.

It is difficult to give a formula for