bles
us to plead a great deal in mitigation. The spectator will notice that
there are no substantial buttresses; and the reason is the simple one
that Wren held them to be disfigurements. "_The Romans always
concealed their Butments._"[77] "_Oblique Positions are Discord to the
Eye unless answered in Pairs, as in the Sides of an equicrural
Triangle.... Gothick Buttresses are all ill-favoured, and were avoided
by the Ancients._"[78] Such were the opinions of Wren; but how was he
to procure stability? The answer is, by the curtain wall. By its dead
weight pressing on the walls of the aisles it renders them stable and
immobile, free from all danger of thrust, while it conceals the
buttresses which render secure the clerestory stage of the building
proper. To paraphrase his own words: "_I do not add buttresses, but I
build up the wall so high as by the addition of this extra weight, I
establish it as firmly as if I had added buttresses._"[79] Thus this
wall performs a double function: it is a substitute for buttresses in
respect to the aisle walls, and a screen for the actual buttresses of
the clerestory stage.

Such is the purpose of the upper story. An ingenious critic who did
not seem to know this vindicates it on the plea that "uninterrupted
altitude of the bulk in the same plane, is absolutely necessary to the
substructure of the mighty dome."[80] No doubt the size of the dome
requires a proportionate rise in the lower elevations; but the fact
remains that the exterior and interior do not correspond. A greater
authority than this critic has thus defined good architecture: "The
essence of good architecture of any kind is that its constructive
system should be put boldly forward, that its decorative system should
be such as in no way conceals or masks the construction, but makes the
constructive features themselves ornamental."[81] And at his uncle's
cathedral of Ely, Wren might have borrowed and worked out an idea
which would have silenced all accusation of fraud and deceit. There,
in the central part of the choir on the south side, the roof was
removed and placed lower down centuries ago, the better to light up
certain shrines below. This roof was never restored to its original
position; and the upper stage of the wall is pierced with empty
windows through which flying-buttresses can now be seen. The effect,
though altogether unusual, is far from displeasing; and the spectator
who remembers that Wren was perfectly fam