Roughly speaking the whole of this dark frame of tones from the accented point of the trees at the top to the mass of the rock on the left, may be said to gradate away into the distance; cut into by the wedge-shaped middle tone of the hills leading to the horizon.
"The Practice and Science Of Drawing"
Harold Speed
From this point the dark and light masses gradate in different directions until they merge above the ships' sails.
"The Practice and Science Of Drawing"
Harold Speed