=The Main Arcade.=--The sides of the piers (east and west) have smaller pilasters, coupled and with narrow panels between, and above these is a plain entablature from which the broad arches rise. This method of making the arches spring from an entablature instead of letting them rest naturally upon the capitals, was an idea borrowed from the Romans, who in turn borrowed it from the Greeks. With the Greeks the entablature was useful, as they had no round arch; and the Romans, just as they borrowed Greek forms and Greek metres for their native Italian literature, in a like spirit borrowed their entablature. It is not necessary, and Freeman calls it a mere _stilt_.[92] The earliest instance we know of its disuse is in the colonnade of the great hall of Diocletian's palace at Spalatro. The greater space of the west severy is diminished by the introduction of detached columns, so that the arches may all be of a like span. These columns, coupled and placed in front of the lesser pilasters, are of white veined marble, and exceedingly graceful. As the arches more immediately rest upon them than upon the pilasters, the Roman use of the entablature as a stilt can be here more clearly seen. I may add that in the church of St. Apollinare Nuovo, at Ravenna, the pillars have only blocks above their capitals, instead of the old entablature reaching from column to column; and this church, built about 500 A.D., accordingly represents the Transition stage between the Roman proper and the Romanesque. Turning next from underneath the arches, and taking our stand in the central aisle, we are in a position to notice the details of the main entablature above the arches. The keystones are ornamented with heads and other pieces of sculpture. As Wren employed so few arches they rise to a great height, and of the different members of the entablature which rests upon the Corinthian capitals of the greater pilasters, part had to be cut away. The crowns of the arches take a great piece out of the architrave, and their keystones reach well within the plain and narrow frieze. Only the cornice of the first stage remains intact, and this runs round the four limbs of the church like a string course in any Romanesque or Gothic building. =The Triforium Belt.=--This used to be called the "Attic," in imitation of the Classical nomenclature; but surely this term is incorrect, since there is a clerestory above, and the vaulting springs from it as well. On the other hand, "Triforium" pure and simple implies arcading, and the above term is adopted from Fergusson as less open to exception.[93] In continuation of the greater pilasters are abutment piers, from the summits of which spring the great arches spanning the nave, the window arches of the clerestory, and the pendentives which connect these with the vaulting. The blank fronts between the piers are relieved by panels, but otherwise destitute of adornment. Openings connect the nave with the galleries behind.