Paul Rehak’s Imperium and Cosmos: Augustus and the Northern Campus Martius was unfinished at the time of the author’s lamentably premature death in 2004. The manuscript was subsequently prepared for publication by his longtime partner and colleague at the University of Kansas, John Younger. In its present version, the book offers a concise study of the major Augustan monuments of the northern Campus Martius in Rome, particularly the Mausoleum, the Ustrinum (cremation site) of Augustus, the Solarium (sun calendar), and the Ara Pacis, the emperor’s famous altar of Peace. It advances the thesis that this part of the city was appropriated by the emperor to connect him ideologically and symbolically with the cosmos—on the one hand, the inhabited world (oikoumene) over which the emperor ruled as a monarch; and on the other hand, the heavens to which he would ascend after his death, and whose resident gods showed him such favor during life.

Posthumous projects of this kind can be hard to evaluate, particularly if one is not party to the author’s intentions. Younger has included an editor’s note suggesting that the book was well on its way to completion. Yet I find aspects of its content unresolved: large sections consist of little more than summaries of the vast body of scholarship on Augustan Rome, particularly as it relates to the monuments of the Campus Martius that principally concern the author. One has the distinct feeling that Rehak had reached a stage in the project that had not quite matured into a full synthesis or argument. The only part of the book with a manifestly developed argument—the discussion in chapter 5 of the Aeneas/Numa relief on the Ara Pacis Augustae—is a reprise of the author’s important 2000 and 2001 articles on the subject published in the American Journal of Archaeology and The Art Bulletin. As the vehicle for a sustained thesis, then, Imperium and Cosmos fails to cohere; but as a summary of the state of early twenty-first-century scholarship on Augustan symbolism in the urbs, it is valuable for both scholars and students.

Certainly the book has a point of view, which current scholarship would deem relatively uncontroversial. It is hard to imagine any but the most doctrinaire partisan taking issue with Rehak’s argument that Augustus’s public imagery—whatever his claims to republican modesty in political life—was unabashedly imperial, even autocratic. Accordingly, as an emperor, Augustus was granted a special relationship to the cosmos, both astrologically and astronomically. His power was presented as preordained and universal, hence the equal emphasis in early Imperial imagery on imperium and cosmos.

While the author gives a more than respectable treatment to the Ustrinum and mausoleum, the book’s core chapters are 4 and 5, on the Solarium and the Ara Pacis respectively. Rehak adheres to the traditional understanding of the Solarium Augusti as a full-scale horologium, or sundial, comprising an enormous, butterfly-shaped grid. As such, it would have been both a calendar and a clock celebrating the emperor, his birthday, his conquest of Egypt and appropriation of its solar cult, and his overall affinity to the cosmos. This model, advanced most vigorously by Edmund Buchner (Die Sonnenuhr des Augustus: Nachdruck aus RM 1976 und 1980 und Nachtrag über die Ausgrabung 1980/1981, Mainz am Rhein: Zabern, 1982; and various subsequent updates) and canonized in most recent studies of Augustan art and urbanism, has been challenged with considerable force and ingenuity by Michael Schütz. In a 1990 article in Gymnasium, Schütz revived a centuries-old argument that the Solarium was nothing more than a north-south meridian line marking the length of the gnomon’s shadow at noon each day of the year (Michael Schütz, “Zur Sonnenuhr des Augustus auf dem Marsfeld,” Gymnasium 97 (1990): 432–57). Rehak tries to address Schütz’s principal arguments, but some of the most important criticisms go unanswered.

It is a pity that this book could not take account of Peter Heslin’s recent article in the 2007 Journal of Roman Studies, which reflects a growing recognition (though far from a consensus) that Buchner’s splendid model of a full-scale sundial is slipping away like the sands of time (Peter Heslin, “Augustus, Domitian and the So-called Horologium Augusti,” The Journal of Roman Studies 97 (2007): 1–20). Buchner has not been able to explain satisfactorily why two pomerial boundary stones—one of Claudius, one of Vespasian—have been found within the field of his proposed grid. More significantly, despite numerous exploratory soundings and excavations, no positive evidence for the grid has yet been found; only the meridian line has revealed a pavement with inscriptions and astrological markings. Rehak does not address Schütz’s important observation that the narrow shadow of the gnomon would dissipate entirely at the considerable distance it must stretch in order to reach the Ara Pacis. If Schütz’s investigation is right, the gnomon was meant simply to be aligned with the Ara Pacis—not, as Buchner would have it, to cast its shadow on the altar’s doorstep at sunset on the emperor’s birthday.

To be sure, either hypothesis fits comfortably into Rehak’s broader thesis of cosmological signification. A simple meridian is less densely meaningful than a fully functioning timepiece, with its hour-markers and symbolism of morning, noon, and evening. But, as Heslin argues, it still emphasizes one of the emperor’s cosmic functions, which he assumed when he took the office of Pontifex Maximus in 12 BCE: the maintenance of the Roman calendar. The grand sweep of time, symbolized by the sun’s passage through the seasons and the houses of the zodiac, is all there, recorded on the meridian. Moreover, I must observe (as Buchner’s critics rarely do) that, even if the desired pavement markings have not been found within the field of the sundial, neither is there any evidence of significant obstructions there. Whatever the “facts on the ground,” the Roman eye could sweep across this open area and fix immediately upon the most significant Augustan monuments in the northern Campus Martius.

Readers of this review will perhaps be most familiar with that warhorse of Roman public art, the Ara Pacis, located due east of the obelisk-gnomon of the Solarium. Chapter 5 is as good, and inclusive, a general introduction to the monument as one is likely to encounter anywhere. True, the author’s thesis gets lost in the discussion, for he feels compelled to present each point of controversy as if it (or the scholarly debates underlying it) were unknown to its readers. Specifically, the treatment of the two long figural friezes of the altar’s outer enclosure is a bit of a slog, as Rehak airs the scholarly debates surrounding the identification of every major figure appearing on them. Whatever the shortcomings of this approach (and again, in all fairness to the author, we cannot know his final intentions), the chapter is the best concise survey of the Ara Pacis, its meanings, and its problems. Many of us, I expect, will be assigning it to our graduate students for their general exams, or to advanced undergraduates searching for an opening to a paper topic.

In fact, the Ara Pacis may well prove to be the monumentum by which Rehak, an art historian of considerable breadth and diverse achievements, is remembered. It has long been assumed that the southern panel on the west side of the Ara Pacis represents Aeneas’s sacrifice of the white sow of Lavinium. Rehak has weakened this seemingly inexorable identification, perhaps beyond redemption, while offering a splendid alternative: the central figure is not Aeneas but Numa, Rome’s second king after Romulus, sacrificing with an attendant foreign king in the Campus Martius to restore peace, thereby establishing the Fetial Law (an institution that Augustus revived). The more time I spend with this extended argument, the more I am persuaded by it. As a man of peace, Numa is a better pendant to Mars—who is shown on the other side of the doorway, probably with the twins Romulus and Remus—than the unambiguously martial Aeneas, and makes a better coaxial companion to the peaceful female “Tellus” figure on the southeast side of the altar enclosure. The popular Aeneas-Romulus pairing, which seems so inevitable to us, was not definitively established until the dedication of the Forum Augustum in 2 BCE, a decade later. Rehak appropriately invokes the Augustan notion that Romulus and Numa represented two sides of a complementary whole. As Livy says, “two successive kings, each in his own way, one by war, the other by peace, increased the nation . . . a nation not only strong, but tempered by the arts of war and peace.” The significance of these two characters, nestled into a unitary ideology like yin and yang, can be broadened to encompass the general meaning of the Ara Pacis, which hangs on the necessary dichotomy of war and peace.

The photographs, all by Rehak or Younger, are adequate but nothing more; Wisconsin’s classical art books are often justly criticized for their drab and sequestered photographic reproductions. For detailed analysis of the monuments, particularly the Ara Pacis, you will need a more lavishly illustrated volume at your disposal as you read the text.