e rash who should make too sure.

In order to live the life of night, a watcher must not wake too much.
That is, he should not alter so greatly the character of night as to lose
the solitude, the visible darkness, or the quietude. The hours of sleep
are too much altered when they are filled by lights and crowds; and
Nature is cheated so, and evaded, and her rhythm broken, as when the
larks caged in populous streets make ineffectual springs and sing
daybreak songs when the London gas is lighted. Nature is easily
deceived; and the muse, like the lark, may be set all astray as to the
hour. You may spend the peculiar hours of sleep amid so much noise and
among so many people that you shall not be aware of them; you may thus
merely force and prolong the day. But to do so is not to live well both
lives; it is not to yield to the daily and nightly rise and fall and to
be cradled in the swing of change.

There surely never was a poet but was now and then rocked in such a
cradle of alternate hours. "It cannot be," says Herbert, "that I am he
on whom Thy tempests fell all night."

It is in the hours of sleep that the mind, by some divine paradox, has
the extremest sense of light. Almost the most shining lines in English
poetry--lines that cast sunrise shadows--are those of Blake, written
confessedly from the side of night, the side of sorrow and dreams, and
those dreams the dreams of little chimney-sweepers; all is as dark as he
can make it with the "bags of soot"; but the boy's dream of the green
plain and the river is too bright for day. So, indeed, is another
brightness of Blake's, which is also, in his poem, a child's dream, and
was certainly conceived by him in the hours of sleep, in which he woke to
write the Songs of Innocence:-

O what land is the land of dreams?
What are its mountains, and what are its streams?
O father, I saw my mother there,
Among the lilies by waters fair.
Among the lambs clothed in white,
She walk'd with her Thomas in sweet delight.

To none but the hours claimed and inspired by sleep, held awake by
sufferance of sleep, belongs such a vision.

Corot also took the brilliant opportunity of the hours of sleep. In some
landscapes of his early manner he has the very light of dreams, and it
was surely because he went abroad at the time when sleep and dreams
claimed his eyes that he was able to see so spiritual an illumination.
Summer is precious for a painter, chiefly beca