I am inclined to believe that while many of the ir-
regularities which give so peculiar an aspect and often
so great a charm of life and variety to the architecture
of Italy in the early Middle Ages are due to the artistic
sense of the builders (as, indeed, it seems to me, Mr. Rus-
kin has proved), others are due to the sinking of foun-
dations and to carelessness in construction, such as we
have evidence of in the erection of the cathedral at
Siena; still others to the irregular supply of material, as
well as to the variety of material brought from ancient
buildings and worked into the new, as was frequently
the case, for instance, in St. Mark's (see ante, p. 56);
and others still to a change of design on the part of
successive builders in works which, like the cathedrals
of Siena and Florence, were labors continued through
many generations.

We should have, then, to make two great distinc-
tions-first, of the originally designed artistic irregu-
larities, productive often of effects of great beauty and
baffling intricacy, the result of fine architectural skill
and feeling; and, second, of originally undesigned ir-
regularities, often injurious to the character of the edi-
fice, and displeasing to the eye, the result of accident,
wilfulness, incompetence, or change of plan. The his-
tory of the building of the Duomo of Siena affords, as
the preceding pages show, many illustrations of the
operation of the latter set of causes of irregularity.

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