emember this, that there is no general way of
doing _any_ thing; no recipe can be given you for so much as the drawing
of a cluster of grass. The grass may be ragged and stiff, or tender and
flowing; sunburnt and sheep-bitten, or rank and languid; fresh or dry;
lustrous or dull: look at it, and try to draw it as it is, and don't
think how somebody "told you to _do_ grass." So a stone may be round and
angular, polished or rough, cracked all over like an ill-glazed teacup,
or as united and broad as the breast of Hercules. It may be as flaky as
a wafer, as powdery as a field puff-ball; it may be knotted like a
ship's hawser, or kneaded like hammered iron, or knit like a Damascus
sabre, or fused like a glass bottle, or crystallised like a hoar-frost,
or veined like a forest leaf: look at it, and don't try to remember how
anybody told you to "do a stone."

As soon as you find that your hand obeys you thoroughly and that you can
render any form with a firmness and truth approaching that of Turner's
and Durer's work,[221] you must add a simple but equally careful light
and shade to your pen drawing, so as to make each study as complete as
possible: for which you must prepare yourself thus. Get, if you have the
means, a good impression of one plate of Turner's Liber Studiorum; if
possible, one of the subjects named in the note below.[222]

If you cannot obtain, or even borrow for a little while, any of these
engravings, you must use a photograph instead (how, I will tell you
presently); but, if you can get the Turner, it will be best. You will
see that it is composed of a firm etching in line, with mezzotint shadow
laid over it. You must first copy the etched part of it accurately; to
which end put the print against the window, and trace slowly with the
_greatest_ care every black line; retrace this on smooth drawing-paper;
and, finally, go over the whole with your pen, looking at the original
plate always, so that if you err at all, it may be on the right side,
not making a line which is too curved or too straight already in the
tracing, _more_ curved or _more_ straight, as you go over it. And in
doing this, never work after you are tired, nor to "get the thing done,"
for if it is badly done, it will be of no use to you. The true zeal and
patience of a quarter of an hour are better than the sulky and
inattentive labour of a whole day. If you have not made the touches
right at the first going over with the pen, retouch them del