The Painter in oil

There are some kinds of subjects, however, which require a complete knowledge of all
the rules of processes of perspective. Whenever you have to construct a picture from
details stated but not seen; when you have a complicated architectural interior or
exterior; when figures are to be placed at certain distances or in definite positions, and
they are too numerous or the conditions are otherwise such that you cannot pose your
models for this purpose; then you may have to make most elaborate perspective plans,
and lay out your picture with great exactness, or the drawing which is fundamental to
such a picture will not be true. Such men as Gérôme and Alma-Tadema plan their
pictures most carefully, and so did Paul Veronese, and it requires a thorough and
practical knowledge of perspective.
But this is not the place to teach you perspective. It is a subject which requires special
study, and whole volumes are given to the elucidation of it. In a work of this kind
anything more than a mention of the bearings of perspective on painting would be out of
place. If you do not care to take up seriously the study of perspective, avoid attempting to
paint any subjects which call for it; or, if you do care to study it, get a special work on
that subject, give plenty of time to it, and study it thoroughly.
Foreshortening. - In this connection I may speak of something which is akin to
perspective, yet the very reverse of it. As its name implies, foreshortening means the way
in which anything seems shortened or in modified drawing as it projects towards you;
while perspective is the manner in which lines appear as they recede from you. Like
aërial perspective, the best way to study foreshortening is to study nature, not rules.
Perspective can be worked out by rule, foreshortening cannot. Pose your model, or if it
be a branch of a tree, or anything of that sort, place yourself in the proper position with
reference to it, and then study the drawing as it appears, thinking nothing of how it is;
make your measurements, and place your lines as if there were no problem of
foreshortening at all, but study the relations of lines, of size, and of values, and the
foreshortening will take care of itself.
After all, foreshortening is only good drawing, and good draughtsman will foreshorten
well, while a bad draughtsman will not. Therefore, learn to draw, and don’t worry about
the foreshortening.