INCREASING PROPENSITY FOR MODULAR
SPACE DIVISION IN PRE-CAROLINGIAN AND
CAROLINGIAN ARCHITECTURE NORTH OF
THE ALPS
The emergence of the square schematism in medieval
architecture depended on two crucial innovations in the
interrelation of the component spaces of the basilican
church:
1. The nave and the transept of the church had to be
given the same width, and
2. The width of the aisles had to be fixed to one-half
the width of the nave.
Without the first, the crossing could not form a square;
without the second, the modular division of the nave could
not be carried into the aisles. Both of these features
occurred separately in Early Christian times, but they were
not integrated then into a programmatic architectural
system.
An example of a church with nave and transept of equal
width is the Justinian basilica of the Nativity at Bethlehem
(if Hans Christ's interpretation of its plan is correct).[293]
In
several Christian churches of Ravenna—all without transepts—the
width of the aisles is fixed at one half, or approximately
one half, the width of the nave. Yet as we survey
Early Christian church architecture as a whole, we must
conclude that its truly distinguishing feature is not the
presence, but rather the absence of any fixed proportions.
Nevenka Petrović[294]
has made an illuminating study of the
proportions in churches of Ravenna and the adjacent
littoral of the Adriatic sea. In attempting to demonstrate
that these churches were laid out according to a system of
squares, as she set out to do, she has de facto illustrated the
fundamental difference between the layout of these later
Early Christian churches and the system of squares employed
in medieval architecture. The salient feature of the
Church of the Plan of St. Gall and its Ottonian and
Romanesque successors is that the squares control the
spacing of the arcades and therefore express the modular
layout of the plan in the elevation of the columns. The
divisions of Petrović's grids (fig. 166), by contrast, have no
relation whatsoever to the position of the arcade columns.
True, in some of the proto-medieval churches of Ravenna,
the length and width of the church exist in a state of
modular interdependency, but since this module does not
control the spacing of the columns, it is aesthetically of no
consequence.
I tend to agree with George Dehio that the square schematism
is essentially a "Germanic" contribution to Western
architecture for two reasons: first, because it is found
primarily in regions of relatively strong Germanic concentration,[295]
and second, because it is in these areas also that
we may detect its developmental antecedents. An early
medieval church exhibiting an incipient tendency toward
the use of the square as a module was Fulrad's church of
St. Denis, begun after 754 and consecrated in 775 (fig.
167).[296]
Its basic layout, if Formigé's interpretation is correct,
was developed within a grid of 6-foot squares which,
in contrast to San Giovanni Evangelista at Ravenna (fig.
166), determined not only the overall dimensions of nave
and transept, but also the interstices of its arcades. The
transept was seven 6-foot units wide, and thirteen long; the
nave was five units wide and fifteen long. The distance from
center to center of arcade columns was two units, and in the
middle part of the transept two cruciform piers establish a
square of five by five units. As yet we cannot speak of
square schematism, because the dimensions of the crossing
square are not mirrored anywhere else in the building, and
in particular not in the intercolumniation of the arcades. A
church that comes closer to this ideal is the Saviour's
Church of Neustadt-on-the-Main, after 768/69 (fig. 167).
The plan of this church together with other cruciform
churches of similar design built in early medieval times,
such as Pfalzel near Trier, and Metlach (both before 713),
may have formed a connecting link between square-divided
Carolingian basilicas of the ninth century and certain
cruciform churches of the fourth and fifth centuries, typical
examples of which are shown in fig. 144-146 and 148-149.
A grandiose variant of this church type, built as early as
380 by Emperor Gratian in his residential city of Trier,
rose in territory that later was part of the very core of the
Frankish kingdom—for every Carolingian to see! (Its
masonry survives to this day, incorporated in the fabric of
the Romanesque church that superseded it.) This is the
only pre-medieval church type where nave and transept
are of equal width, their intersecting bodies forming a
square—and one might indeed regard the fully developed
square schematism of the Carolingian period as a transference
to churches of basilican plan of a principle already
experimented with in pre-medieval times in the highly
specialized context of these Early Christian cross-in-square
churches.
[297]
The first Carolingian church to mark the developmentally
significant moment of the adoption of the
square schematism in a building of unequivocally basilican
design was the abbey church of Centula, 790-799, if
Irmingard Achter's reconstruction of this building is
correct (fig. 170).
[298]
Because of the scarcity of archaeological
data available on this important building, such an assumption
can neither be fully accepted nor convincingly
rejected. For the same reason it is impossible to ascertain
whether the interstices of the nave arcades were aligned
with these modules.
Modular adjustment between width and length of the
component spaces is clearly visible, however, in the abbey
church of Fulda (802-817).[299]
Its nave, measured from the
base of its western to that of its eastern apse, was exactly
four times its width (fig. 169). The dimensions of the
transept were identical with those of the nave. In the vast
body of literature devoted to Fulda—whose authors never
weary of citing the dependence of its design on that of Old
St. Peter's—this crucial aesthetic novelty has never been
pointed out, much less set into proper historical perspective.
We know nothing about the intercolumniation of
Fulda.
On the other hand, it is not possible to interpret Old
St. Peter's as having been developed within a grid of
identical squares—neither each volume by itself, nor any
volume in relation to a neighboring unit or to the whole of
the building mass. The architect who planned St. Peter's
employed instead a constructional system as classical in
concept as the modularity of the Carolingian churches
shown in figs. 144ff is medieval (see Born's analysis, fig.
170). He calculated the length of the longitudinal body of
the church by making use of the diagonal of a square with a
side equal to the width of the church, and developed the
overall length of the church in the same manner, with the
aid of the diagonal of the rectangle obtained by the preceding
method. This configuration, known as a √2
rectangle, is irrational, since the diagonal of a square is not
in any integral relationship to its sides (1: √2 = 1:1.414)
and therefore cannot be defined as an aggregation of an
integral modular value.
Hildebold's church of Cologne (ca. 800-819) was
composed wholly of equal squares: three in the transept,
four in the nave, one in the fore choir (fig. 172). If the
elevation of its nave walls was identical with that of the
church dedicated in 870, the piers of the arcades that
carried the clerestory walls would not have been in alignment
with this system.
The abbey church of Reichenau-Mittelzell, built by
Haito (806-816) is also developed within a modular grid of
squares, but the grid is irregular, and its existence, for that
reason, has been questioned. In evaluating this problem it
is important to distinguish the existence or nonexistence of
the concept of squares at Reichenau from the regularity or
perfection of its execution. The irregularity, in the angular
deviation of the walls from the grid (especially noticeable in
the eastern part of the church) is caused by special topographical
conditions. But no doubt can be entertained that
the concept exists. The shape of the fore choir and of the two
transept arms are almost a mirror image of the shape of the
crossing square, but the squares of the nave are slightly
oblong. Yet the principle of divisions is clearly there, and
the boundary between the two oblongs of the nave is
marked by piers, whose design differs from the columns
standing midway between them. In this feature St. Mary's
Church at Reichenau goes a step beyond even the Church
of the Plan of St. Gall, which has no such alternation in its
main supports.
In Hildebold's church of Cologne (fig. 172) the system
of squares finds clear expression in the west transept and
in the eastern fore choir, both of which are formed of squares
of identical size: three in the transept, one in the fore choir.
The nave is composed of four squares of like dimensions.
We know nothing about its elevation. If it was identical
with that of the church that was dedicated in 870, the piers
of the arcades which carry the clerestory walls would not
have been in alignment with the system of squares.
In the Church of the Plan of St. Gall the square schematism
attains its purest Carolingian form of expression (fig.
173). The basic unit is the 40-foot module of the crossing
square. The transept is formed of three such squares, the
fore choir of one, the nave of four and one-half; and the
dimensions of the crossing square are echoed even in the
Library and Vestiary. In St. Gall, moreover, the interstices
of the columns are in rhythmical alignment with the
squares. It is incomprehensible to me how this fact should
ever have been questioned. What the designer of this
church had in mind were arcades cutting deep into the
masonry of the nave walls (fig. 110) with their supports so
spaced as to give bodily expression to the sequence of
squares on which the Plan was based. This schematism is
a conscious and willed aesthetic principle. It is a fundamentally
different concept from that which produced the
low, narrowly spaced columnar orders of the Early Christian
basilicas of Rome (figs. 141 and 174). Contrary to what
Guyer, Reinhardt, and Reinle believe, it is an ingenious
anticipation of the square schematism of the Romanesque.
What are the historical preconditions of this propensity
for modular organization of space? Some clearly are functional.
Others may have to be traced to vernacular architecture.
For still others we shall have to reach, beyond the
boundaries of architectural history, into the field of book
illumination, where strong expression of modular modes
of thinking can be observed over a century before they
assert themselves in church building. Yet others, and perhaps
the most important of all, may have to be sought in
deeper and more general cultural levels.
