objects have a tendency to do very much the same thing as this
ancient people did, or even to emulate the mathematician and represent
things not as they appear but as they are, and will make the top of a
table an almost upright square and the objects upon it as if they would
fall off.

No doubt the Greeks had correct notions of perspective, for the
paintings on vases, and at Pompeii and Herculaneum, which were either by
Greek artists or copied from Greek pictures, show some knowledge, though
not complete knowledge, of this science. Indeed, it is difficult to
conceive of any great artist making his perspective very wrong, for if
he can draw the human figure as the Greeks did, surely he can draw an
angle.

The Japanese, who are great observers of nature, seem to have got at
their perspective by copying what they saw, and, although they are not
quite correct in a few things, they convey the idea of distance and make
their horizontal planes look level, which are two important things in
perspective. Some of their landscapes are beautiful; their trees,
flowers, and foliage exquisitely drawn and arranged with the greatest
taste; whilst there is a character and go about their figures and birds,
&c., that can hardly be surpassed. All their pictures are lively and
intelligent and appear to be executed with ease, which shows their
authors to be complete masters of their craft.

The same may be said of the Chinese, although their perspective is more
decorative than true, and whilst their taste is exquisite their whole
art is much more conventional and traditional, and does not remind us of
nature like that of the Japanese.

We may see defects in the perspective of the ancients, in the mediaeval
painters, in the Japanese and Chinese, but are we always right
ourselves? Even in celebrated pictures by old and modern masters there
are occasionally errors that might easily have been avoided, if a ready
means of settling the difficulty were at hand. We should endeavour then
to make this study as simple, as easy, and as complete as possible, to
show clear evidence of its correctness (according to its conditions),
and at the same time to serve as a guide on any and all occasions that
we may require it.

To illustrate what is perspective, and as an experiment that any one can
make, whether artist or not, let us stand at a window that looks out on
to a courtyard or a street or a garden, &c., and trace with a
paint-brush charged with Ind