y be enjoyed after labour; sound, to be heard clearly, must
rise out of silence; light is exhibited by darkness, darkness by light;
and so on in all things. Now in art every colour has an opponent colour,
which, if brought near it, will relieve it more completely than any
other; so, also, every form and line may be made more striking to the
eye by an opponent form or line near them; a curved line is set off by a
straight one, a massy form by a slight one, and so on; and in all good
work nearly double the value, which any given colour or form would have
uncombined, is given to each by contrast.[257]

In this case again, however, a too manifest use of the artifice
vulgarises a picture. Great painters do not commonly, or very visibly,
admit violent contrast. They introduce it by stealth and with
intermediate links of tender change; allowing, indeed, the opposition to
tell upon the mind as a surprise, but not as a shock.[258]

Thus in the rock of Ehrenbreitstein, Fig. 35., the main current of the
lines being downwards, in a convex swell, they are suddenly stopped at
the lowest tower by a counter series of beds, directed nearly straight
across them. This adverse force sets off and relieves the great
curvature, but it is reconciled to it by a series of radiating lines
below, which at first sympathize with the oblique bar, then gradually
get steeper, till they meet and join in the fall of the great curve. No
passage, however intentionally monotonous, is ever introduced by a good
artist without _some_ slight counter current of this kind; so much,
indeed, do the great composers feel the necessity of it, that they will
even do things purposely ill or unsatisfactorily, in order to give
greater value to their well-doing in other places. In a skilful poet's
versification the so-called bad or inferior lines are not inferior
because he could not do them better, but because he feels that if all
were equally weighty, there would be no real sense of weight anywhere;
if all were equally melodious, the melody itself would be fatiguing; and
he purposely introduces the labouring or discordant verse, that the full
ring may be felt in his main sentence, and the finished sweetness in his
chosen rhythm.[259] And continually in painting, inferior artists
destroy their work by giving too much of all that they think is good,
while the great painter gives just enough to be enjoyed, and passes to
an opposite kind of enjoyment, or to an inferior state