It may have been difficult in the past to describe various elements of the process of planning, designing and constructing architecture, and to consider the importance of each of these activities—not only as separate entities or disciplines, but also—and predominantly—in relation to each other. This problem is demonstrated by Vitruvius, who has carved out a formidable position for himself in the history of architecture and architectural theory. Even though his De architectura libri decem is of immense importance for our understanding of the architecture of antiquity, it is hard to gain a proper understanding of the fields of architecture described by Vitruvius commonly called practice and theory. To formulate it more clearly: reading Vitruvius, it is not always easy to distinguish when the author describes common practice, or common theory; or when he focuses on a descriptive or normative kind of rule.

Though it may often be possible to avoid this problematic side of Vitruvius's treatise, that is certainly not always the case. As Mario Carpo notes in his Architecture in the Age of Printing: “With its elaborate yet confusing mode of expression, its uncertain syntax, and its inventive hybrid vocabulary of Greek and Latin terms, the Vitruvian text is discouragingly obscure.” As Carpo mentions, Vitruvius seems to apologize for any obscurity in his text, noting that he did his best ”…as far as [he] could indicate by writing” (“quoad potui significare scriptis, exposui”). According to Carpo, one reason for the problematic nature of the text is the absence of illustrations. The text is also difficult to comprehend because of its entanglement of the ideals of theory with the realities of practice, which is what concerns me here.

In much later times, architectural theory evolved into a discipline in its own right, no longer serving as a practical how-to-build guide, since theory does not always have a clear connection to the practice of designing and building. Yet the connection between architectural practice and written theory developed a problematic side, especially in those instances in which the texts relied on examples taken from extant buildings. Vitruvius and many architects and architectural authors in the Renaissance were looking for design rules. They went out of their way to build according to rules and methods that were considered necessary for beautiful and good architecture.