Lectures on Landscape by John Ruskin

28. In my last Lecture I laid before you evidence that the greatness of the master whom I wished you to follow as your only guide in landscape depended primarily on his studying from Nature always with the point; that is to say, in pencil or pen outline. To-day I wish to show you that his preeminence depends secondarily on his perfect rendering of form and distance by light and shade, before he admits a thought of color.

I say "before" however -- observe carefully -- only with reference to the construction of any given picture, not with reference to the order in which he learnt his mechanical processes. From the beginning, he worked out of doors with the point, but indoors with the brush; and attains perfect skill in washing flat color long before he attains anything like skill in delineation of form.