itted. The only uses,
therefore, of rock form which are wise in the architect, are its actual
introduction (by leaving untouched such blocks as are meant for rough
service), and that noble use of the general examples of mountain
structure of which I have often heretofore spoken. Imitations of rock
form have, for the most part, been confined to periods of degraded
feeling and to architectural toys or pieces of dramatic effect,--the
Calvaries and holy sepulchres of Romanism, or the grottoes and fountains
of English gardens. They were, however, not unfrequent in mediaeval
bas-reliefs; very curiously and elaborately treated by Ghiberti on the
doors of Florence, and in religious sculpture necessarily introduced
wherever the life of the anchorite was to be expressed. They were rarely
introduced as of ornamental character, but for particular service and
expression; we shall see an interesting example in the Ducal Palace at
Venice.

Sec. XXIII. But against crystalline form, which is the completely
systematised natural structure of the earth, none of these objections
hold good, and, accordingly, it is an endless element of decoration,
where higher conditions of structure cannot be represented. The
four-sided pyramid, perhaps the most frequent of all natural crystals,
is called in architecture a dogtooth; its use is quite limitless, and
always beautiful: the cube and rhomb are almost equally frequent in
chequers and dentils: and all mouldings of the middle Gothic are little
more than representations of the canaliculated crystals of the beryl,
and such other minerals:

Sec. XXIV. Not knowingly. I do not suppose a single hint was ever actually
taken from mineral form; not even by the Arabs in their stalactite
pendants and vaults: all that I mean to allege is, that beautiful
ornament, wherever found, or however invented, is always either an
intentional or unintentional copy of some constant natural form; and
that in this particular instance, the pleasure we have in these
geometrical figures of our own invention, is dependent for all its
acuteness on the natural tendency impressed on us by our Creator to love
the forms into which the earth He gave us to tread, and out of which He
formed our bodies, knit itself as it was separated from the deep.

Sec. XXV. 3. Forms of Water (Waves).

The reasons which prevent rocks from being used for ornament repress
still more forcibly the portraiture of the sea. Yet the constant
necessity of i