divided up into small and inferior rooms, filled in as well as may be
behind the architectural design--the whole design is in that case only
a blind or screen, giving a false exterior symmetry to a building which
is not so planned. This is an extreme case (or might be called so if it
were not actually of pretty frequent occurrence); but it illustrates in
a broad sense a principle which must be carried out in all cases, if the
architecture is to be a real expression of the facts of the building.

In this lecture, which is concerned with general principles, a word may
fittingly be said as to the subject of _proportion_, concerning which
there are many misapprehensions. The word may be, and is, used in two
senses, first in regard to the general idea suggested in the words "a
well proportioned building." This expression, often vaguely used, seems
to signify a building in which the balance of parts is such as to
produce an agreeable impression of completeness and repose. There is a
curious kind of popular fallacy in regard to this subject, illustrated
in the remark which used to be often made about St. Peter's, that it is
so well proportioned that you are not aware of its great size, etc.--a
criticism which has been slain over and over again, but continues to
come to life again. The fact that this building does not show its size
is true. But the inference drawn is the very reverse of the truth. One
object in architectural design is to give full value to the size of a
building, even to magnify its apparent size; and St. Peter's does not
show its size, because it is _ill_ proportioned, being merely like a
smaller building, with all its parts magnified. Hence the deception to
the eye, which sees details which it is accustomed to see on a smaller
scale, and underrates their actual size, which is only to be ascertained
by deliberate investigation. This confusion as to scale is a weakness
inherent in the classical forms of columnar architecture, in which the
scale of all the parts is always in the same proportion to each other