colours to compose a tone; it is again artificial that paints have been
invented which represent some of the combinations of the spectrum, just
to save the artist the trouble of constantly mixing the seven solar
tones. Such mixtures are false, and they have the disadvantage of
creating heavy tonalities, since the coarse mixture of powders and oils
cannot accomplish the action of light which reunites the luminous waves
into an intense white of unimpaired transparency. The colours mixed on
the palette compose a dirty grey. What, then, is the painter to do, who
is anxious to approach, as near as our poor human means will allow, that
divine fairyland of nature? Here we touch upon the very foundations of
Impressionism. The painter will have to paint with only the seven
colours of the spectrum, and discard all the others: that is what Claude
Monet has done boldly, adding to them only white and black. He will,
furthermore, instead of composing mixtures on his palette, place upon
his canvas touches of none but the seven colours _juxtaposed_, and leave
the individual rays of each of these colours to blend at a certain
distance, so as to act like sunlight itself upon the eye of the
beholder.

[Illustration: DEGAS

WAITING]

This, then, is the theory of the _dissociation of tones_, which is the
main point of Impressionist technique. It has the immense advantage of
suppressing all mixtures, of leaving to each colour its proper strength,
and consequently its freshness and brilliancy. At the same time the
difficulties are extreme. The painter's eye must be admirably subtle.
Light becomes the sole subject of the picture; the interest of the
object upon which it plays is secondary. Painting thus conceived becomes