If you cannot arrange that those who look at your work should stand
at one particular point, when constructing your work, stand back
until your eye is at least 20 times as far off as the greatest
height and width of your work. This will make so little difference
when the eye of the spectator moves, that it will be hardly
appreciable, and it will look very good.

If the point of sight is at _t_ you would make the figures on the
circle _d b e_ all of one size, as each of them bears the same
relation to the point _t_. But consider the diagram given below and
you will see that this is wrong, and why I shall make _b_ smaller
than _d e_ [Footnote 8: The second diagram of this chapter stands in
the original between lines 8 and 9.].

It is easy to understand that if 2 objects equal to each other are
placed side by side the one at 3 braccia distance looks smaller than
that placed at 2 braccia. This however is rather theoretical than
for practice, because you stand close by [Footnote 11: Instead of
'_se preso_' (=_sie presso_) M. RAVAISSON reads '_sempre se_' which
gives rise to the unmeaning rendering: '_parceque toujours_ ...'].

All the objects in the foreground, whether large or small, are to be
drawn of their proper size, and if you see them from a distance they
will appear just as they ought, and if you see them close they will
diminish of themselves.

[Footnote 15: Compare No. 526 line 18.] Take care that the vertical
plan on which you work out the perspective of the objects seen is of
the same form as the wall on which the work is to be executed.