The interior of the Pantheon embodies the classical idea of space as a room. A room has boundaries, is governed by proportion, and is characterized by human intentions. A room always has a sense of direction toward a center or along an axis. Its bounding surfaces are neither arbitrary nor indistinct but are as inseparable from the room itself as a mold is from the shape of the material cast within it.
At the Pantheon, we are struck by the sheer expansiveness of the space and, at the same time, by its comforting boundedness. As the curvature of the dome draws the eye upward, the enclosing wall embraces us and at the same time reveals further spaces beyond the encircling columns. Above us, the oculus at the center of the dome opens to the sky. The story of any classical room is always, in part, just such a dialogue between enclosure and expansion.
While the Greeks had used the Corinthian capital with an Ionic entablature, the Romans invented a distinct cornice for the Corinthian order, characterized by large projecting modillions embellished with acanthus leaves.
The opulence of the Corinthian is amply illustrated by the order of the Pantheon, and in all of classical architecture no other element more perfectly captures the balance of formal geometry and sensuous delight. Any room articulated in a full Corinthian order becomes a place of importance and majesty.
Despite the seemingly perfect formal design of the capital in its canonic form, there has been subtle but significant variation in the details of this order since antiquity. The Romans frequently varied the composition and decorative details of the capital, sometimes altering the arrangement of the volutes or leaves, as in those for the pilasters of the upper tier of the Pantheon, where the volutes become graceful double scrolls meeting in the lower center of the capital above a single row of leaves.
As the layers of structure, orders, and various individual elements ply across the Pantheon's bounding surfaces, a complex pattern of articulation emerges, organizing all the parts into a satisfying whole. We see in the Pantheon an illustration of classical composition worked out simultaneously in three dimensions and at a number of different scales.
The walls, for example, are organized by an elaborate framework comprising columns, the lintels they carry, niches, doorways, and the areas of wall surface between these other elements, themselves further subdivided into shapes of various kinds. Alternating solids and voids are precisely placed and the relations among these elements very carefully worked out.
The room is a three-dimensional puzzle whose distinctive pieces enter into complex relationships with one another in response to functional need, structural logic, and aesthetic judgment. The Pantheon's composition is hierarchical, syncopated, and subtle. The overall impression is one of interlocking orderliness rather than a mere aggregation of parts, of a body rather than a machine.
Composition (literally, "putting it together") is the essence of classical design because it coordinates everything. Space, structure, the orders, and the elements might each go their separate ways (and in weak or poorly designed rooms often do) if the overall discipline of composition does not unify them.
Composition achieves this aim by manipulating two closely related essentials of design: arrangement and scale. Arrangement assigns to every element and every detail its proper role and place within the whole ensemble. Scale controls the perceived size of the elements and details with respect to one another and to a human observer.
Light and Color
The Pantheon is a paradigm of the literal and metaphorical use of light to shape space. The sun streams in through the open oculus, tracing a circular disk across the walls and floor, creating a walk-in solar observatory. The column screens and niches around the room create a mysterious and alluring chiaroscuro effect.
Even on a cloudy day the light beaming through the top of the dome seems to represent the ineffable visitation of divine beauty. The rain descends from the oculus in a columnar, shimmering shower, thunder echoes around the inside the dome, and I have even seen lightning streak across the opening. However perfect its symmetry and proportions, a room might still leave us cold without such direct appeals to the eye, the body, and the spirit.
The effect of a room transformed by light cannot be explained solely in objective or quantifiable terms but forces us to recognize the metaphorical role of light. We speak of the light of reason, the light of truth, and the light of eternity. All of these may come to mind as we stand beneath the Pantheon's oculus. Light is perhaps the one unambiguous symbol available to the architect should the occasion call for it, regardless of style or culture.
A visitor to the Pantheon quickly realizes that the classical interior welcomes the sensuous appeal of light effects and the beauties of the forms and materials revealed by light. The many-colored marbles with which the interior is sheathed, originally brightly polished and with details picked out in gold, demonstrate the Roman love of splendor.
The columns and pilasters of the lower zone are giallo antico (a yellowish-orange marble) and pavonazzo (off-white with streaks of reddish-purple), while deep red Egyptian porphyry contrasts with white, green, and green-gray marble in the floor and wall sheathing. The colors are exceptionally well balanced and present a lively display of hue, value, and tonality inseparable from our perception of the whole space.
Following the collapse of Roman civilization in the fifth century, the classical tradition continued in the Byzantine world but faded from view in Western Europe until it was rediscovered and revived a millennium later during the Italian Renaissance.
Renaissance architects invented a new architecture based on the models of surviving ancient buildings, but incorporating significant innovation. By virtue of its built examples and the treatises written by its major practitioners, the rebirth of classical architecture in Italy soon spread to France and England, then to all of Europe and, finally, to the New World. The tradition continued to grow and diversify until by the mid-18th century it had been adapted to the widest conceivable variety of building purposes, types, materials, climates, and cultures.
In our own time, artists are reviving the classical yet again, relearning the historical languages while confronting new programs and new technologies. We find ourselves today in the midst of the latest in a series of renaissances that have periodically refreshed the classical throughout the history of Western art.
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Steven W. Semes is Rooney Professor of Architecture at the University of Notre Dame and a practicing architect in New York City. He is a fellow of the Institute of Classical Architecture and Classical America. He teaches and writes regularly on classical architecture and design.
This article is excerpted from The Architecture of the Classical Interior, copyright © 2004, available from W.W. Norton & Company, Inc. and at Amazon.com.