Published in 1679, René Ouvrard's slim treatise outlines a “harmonic” approach to architecture, based on the ratios of musical intervals, including the octave (2:1), perfect fifth (3:2), perfect fourth (4:3), major third (5:4), minor third (6:5), and their octave equivalences. Ouvrard reasons that because these and only these proportions deliver agreeable results in music, similar proportions will produce equally pleasing outcomes in architecture. Conversely, unharmonious proportions will generate dissonant effects that are shocking to the eye. He cites the Temple of Solomon as a historical example of harmonic architecture. At 60 cubits in length, 20 in width, and 30 in height, the temple's dimensions embodied both the octave (60:30 or 2:1) and the perfect fifth (30:20 or 3:2). The Greeks and Romans also designed their edifices to harmonic specifications, according to Ouvrard, and he concludes his treatise by reproducing, with brief commentary, two excerpts from Vitruvius's De architectura. His goal throughout the treatise is to push back against what he considered to be the arbitrary principles guiding the design of contemporary architecture in France.

Because of the work's brevity, simplicity of argument, and accessibility (a digital copy of the original publication is freely available online through Gallica), the primary value of the current edition of Architecture harmonique lies in the critical introduction presented by the editor, Vasco Zara. One of Zara's main objectives is to convince the reader to care about Ouvrard's little-known treatise at all. Fortunately, the circumstances surrounding its genesis are compelling. As maître de musique of the Sainte-Chapelle du Palais, in Paris, Ouvrard worked alongside some of the kingdom's most powerful men, including Jean-Baptiste Colbert, who entrusted to Ouvrard the education of his son Jules-Armand. It was Colbert's commitment to forging a distinct architectural tradition in France through the expansion of the Louvre—in particular the east façade—and the founding of the Académie Royale d'Architecture, in 1671, that inspired Ouvrard's Architecture harmonique. As Zara shows, the work was meant to offer a framework for future French architecture, one rooted in antiquity, objectivity, and a belief in the unity of art forms. Its intended audience included Colbert (to whom the work is dedicated) and a number of architects and theorists interested in similar issues, in particular Claude Perrault, who advanced an architectural agenda diametrically opposed to Ouvrard's. He denied the analogy central to the latter's argument—namely, that what pleases the ear must necessarily please the eye. Like his brother Charles, who made clear and disapproving allusions to Ouvrard in his Parallèle des Anciens et des Modernes (1688–97), Perrault was comfortable attributing architectural beauty to convention, habituation, and individual taste, rather than to any objective mathematical underpinnings supposedly discovered by the ancients.

Zara deftly demonstrates the extent to which Perrault and Ouvrard read and responded to each other's arguments in their own writings. Indeed, he is very good at situating Ouvrard's treatise in the context of a broader debate over the relative merits of ancient wisdom and modern innovation. Although the start of the Querelle des Anciens et des Modernes is usually dated to 1687, Zara makes the case for an anticipatory “Querelle des Proportions en Architecture” (39) in the 1670s and 1680s, which covered some of the same issues and much of the epistemological terrain as the later, more famous debate. Ouvrard ultimately lost out to the forces of modernity, his ideas on ancient architecture disproved by the careful measurements of Roman buildings undertaken by Antoine Desgodets. Both the treatise and its author fell into obscurity: in 1692 Christiaan Huygens advised Leibniz not to read the “extravagant” treatise (54), and by the mid-eighteenth century the work was completely forgotten. Nevertheless, Ouvrard's strange marriage of music and architecture helps to illuminate an exciting moment in French intellectual history, and scholars interested in either field should welcome Zara's new edition.