VITRUVIUS. 
Tus dispostion of the work, the artifters, when they ereded facred edices, imtated 
in feulorures of fone and matble; and this invention the ancient vorkmen thought properto 
nufhe. Thus, whenever they conftuded any building, they lad the joists from the interior 
valleto the esteme parts, then buile up the interjoist (4), and, to give the work a pleasing 
appearance, adorned the top with a cornice and fastigium; then, as much of the joits as 
projedted beyond the wall they sawed off; which appearing unhandsome, they made tablets sh 
like the triglyphs now in ule, fixed them against the sawed ends of the joists, and painted 
them in wax, that the sectures of the joists might not offend the sight. Thus the trigyphs, 
interjoists, and opa, in Doric work, had their origin from the disposition of the timbers of 
the roof. 
AFTERWARD, in other works, some made the canthers, that were perpendicularly over the 
triglyphs, to project outward, and carved their projecture; hence, as the triglyphs arose 
from the disposition of the joists, so the mutules under the corona were derived from the 
projecture of the canthers: wherefore, in stone or marble structures, the mutules are represented 
declining, in imitation of the canthers; and also, on account of the droppings from the eaves, 
it is proper they should have such declination. 
FROM this imitation, therefore, arose the use of triglyphs and mutules in Doric work: for 
it cannot be, as some erroneously assert, that the triglyphs represent windows; because 
triglyphs are disposed in the angles, and over the quarters of the columns, in which places 
windows are not permitted; for if windows were there left, the union of the angles of 
buildings would be dissolved; also, if the triglyphs are supposed to be situated in the place 
of the windows, by the same reason, the dentils in lonic work may be thought to occupy the 
places of the windows; for the intervals between the dentils, as well as between the triglyphs, 
are called metopæ; the Greeks calling the bed of the joists and assers, opas, (as we call it cava, 
columbaria) ; so because the interjoist is between two opae, it is by them called met-opae. As 
the triglyphs and mutules in the Doric order are founded upon these principles, so the dentils, 
in the lonic, derive their proper origin from the workmanship; and as the mutules represent 
the projectures of the canthers, the dentils in the lonic order are in imitation of the projecture 
of the assers. For this reason, in Grecian buildings, dentils are never placed under the 
mutules; for assers cannot be under canthers. As therefore they should in reality be above 
the canthers and templats, if they are represented below them, the work is on false principles. 
The ancients likewise did not approve of placing mutules or dentils in the fastigium, but the 
(2*) Opae is explained farther on in this chapter. 
(3') In the ruins of the Grecian buildings at Athens, 
and allo in some at Poestum, in Italy, we find the triglyphs 
placed close to the angles, not perpendicularly over the 
middle of the columns, as practised in the Roman as wel 
as modern architecture, 
(4*) By this expression we are to understand the middle 
of the celumns; for the quarters of the columns, l suppose, 
mean the four parts of the column, when divided on the 
plan, by two diagonal lines passing through the center at 
right angles to each other, in the form of a cross, thus, 
. In the next chapter Vitruvius calls them the middle 
quarters, which are the two quarters a and o in the middle 
of the front and rear of a column so divided, having the two 
other quarters b and c on either side them.