354
(Latin: virtus, adeptness, fitness) encompasses all of those
phenomena and features that, while not physically grasp-
able, are nonetheless essential to architecture, in particular its
spatial > atmosphere, > gesture, and the guiding of > move-
ment. At the elementary level of simple perception already, we
experience architecture virtually in the sense that it conveys
to us some conception of its possibilities for interaction and
movement and of its spaces, even before we actually lay claim
to them. It facilitates orientation and provides us with some
conception of visually inaccessible areas, for example those
behind our backs, or on the other side of walls. All > form
characters, whether weighty, floating, receptive or forbidding,
are virtual. Virtual as well, finally, are all types of feeling for
space and its character, including impressions of > size, nar-
rowness and > expansiveness, > closedness and > directional-
ity, and all corporeal spatial relationships. In many cases, such
forms of virtuality shape our interaction with architecture
more decisively than its physical properties. Inherent in them
is a genuinely fundamental capacity of architecture.
On the other hand, it is a question of exaggeration when
virtual effects are used for the sake of perceptual corrections,
illusion and deception. Here we find the optical corrections
to the architectural elements of the Greek temple, including
curvatures in the horizontal or inclinations and entasis in col-
umns, which allow architecture to seem alive. The illusionistic
ceiling frescoes of the Baroque allow a closed space to seem
open above, bearing the beholder aloft with ecstatic gestures
into a celestial realm. In Francesco Borromini’s colonnade at
Palazzo Spada in Rome, a perspectival illusion is generated
by having all of the details of a passageway that narrows as it
proceeds progressively reduced in size so that it seems much
longer than it actually is. A sense of oppression is triggered by
the apparent inescapability of a labyrinth, and bewilderment
is achieved by the multiplication of space within a mirrored
cabinet by means of mirrored mirror images. In his project
for a cenotaph for Newton, Étienne-Louis Boullée wanted to