rightly adjusted, and leaves nothing defective in the appearance. For some objects are to be 
viewed near, others elevated; some are inclosed, others exposed; in all which, great judgment 
is required to modify them so that at last the work may be perfect: for the sight does not 
always inform justly, but often differs from the judgment; as in painted scenes, where columns, 
mutules, and statues, seem to project and be prominent, although they are undoubtedly flat 
planes. The oars of ships likewise, when under water, are really straight, notwithstanding 
they appear to the eye to be crooked; for the instant before their ends touch the surface of 
the water they appear straight, as they are; yet as soon as they are plunged into the water, 
by means of the transparent medium, their images are refracted toward the surface, and cause 
(1*) This passage affords good reason for believing 
that the antients well understood the art of perspective, 
which some have doubted on account of the defective 
examples of it which have come to our knowledge 
See also the Proem to the seventh book. 
(2*) Vitruvius speaks according to the philosophy of 
his time in accounting for the crooked appearance of 
oars in the water; which is now known to be caused by 
the refraction of the rays of light passing through that 
denser medium. 
B00 K: VI. 
CHAPTER II. 
Of the Proportions of private Buildings. 
NOTHING ought to be more the care of an Architect, than that the several parts of 
an edifice be in exact proportion; when therefore the kind of symmetry and the magnitudes 
are settled, it is then the part of the judgment to adapt them to the nature of the place, the 
use, or the species, and, by diminution or addition, to qualify the symmetry, till it appears 
them to appear crooked; and whether this be owing to the impulse of the images, or to the 
divergence of the rays from the eyes, whichever philosophers will admit, we however find that 
either way the eyes are deceived. As then things may appear falsely, and may be different 
from what they seem to the eyes, I think it cannot be doubted, but that we should diminish 
or enlarge objects according to the nature of their situation, in order that no pait of the 
work may be unsatisfactory; but this must be effected by the acutenes of genius, and cannot 
be taught by precepts. 
(3*) The subject here treated of, viz. altering the 
usual proportions of objects when placed in some situa- 
tions, or under some peculiar circumstances, is a point 
much contested. 
In first determining or selecting the proportion to be 
given to an object, regard must undoubtedly be paid to 
its use, place, or other circumstances; but that being 
done, whether a deviation therefrom may on any account 
be proper, is the question. 
The only, or chief, reason that occurs to me for such 
deviation, is that without it the object, when in its place,