lyphs. The Greeks call the seats of tie-beams and rafters
[Greek: opai], while our people call these cavities columbaria
(dovecotes). Hence, the space between the tie-beams, being the space
between two "opae," was named by them [Greek: metope].

5. The system of triglyphs and mutules was invented for the Doric order,
and similarly the scheme of dentils belongs to the Ionic, in which there
are proper grounds for its use in buildings. Just as mutules represent
the projection of the principal rafters, so dentils in the Ionic are an
imitation of the projections of the common rafters. And so in Greek
works nobody ever put dentils under mutules, as it is impossible that
common rafters should be underneath principal rafters. Therefore, if
that which in the original must be placed above the principal rafters,
is put in the copy below them, the result will be a work constructed on
false principles. Neither did the ancients approve of or employ mutules
or dentils in pediments, but only plain coronae, for the reason that
neither principal nor common rafters tail into the fronts of pediments,
nor can they overhang them, but they are laid with a slope towards the
eaves. Hence the ancients held that what could not happen in the
original would have no valid reason for existence in the copy.

6. For in all their works they proceeded on definite principles of
fitness and in ways derived from the truth of Nature. Thus they reached
perfection, approving only those things which, if challenged, can be
explained on grounds of the truth. Hence, from the sources which have
been described they established and left us the rules of symmetry and
proportion for each order. Following in their steps, I have spoken above
on the Ionic and Corinthian styles, and I shall now briefly explain the
theory of the Doric and its general appearance.

CHAPTER III

PROPORTIONS OF DORIC TEMPLES

1. Some of the ancient architects said that the Doric order ought not to
be used for temples, because faults and incongruities were caused by the
laws of its symmetry. Arcesius and Pytheos said so, as well as
Hermogenes. He, for instance, after getting together a supply of marble
for the construction of a Doric temple, changed his mind and built an
Ionic temple to Father Bacchus with the same materials. This is not
because it is unlovely in appearance or origin or dignity of form, but
because the arrangement of the triglyphs and metopes (lacunaria) is an
embarr