Meaning: This quote is attributed to Marcus Pollio, a Roman architect, engineer, and author who lived during the first century BCE. He is also known as Vitruvius, and he is most famous for his work "De architectura" (On Architecture), which is the only surviving major book on architecture from classical antiquity. The quote itself pertains to the design and construction of walls, specifically emphasizing the importance of their thickness.

In the context of architecture and construction, the thickness of walls has always been a crucial factor in ensuring the structural integrity and functionality of a building. Vitruvius's quote underscores the practical aspect of wall thickness, as it directly relates to the ease of movement and the potential for defense within a space. The requirement for two armed men to pass each other with ease implies not only the necessity for adequate space but also the consideration of potential defensive scenarios where multiple individuals may need to move within or alongside the walls.

The significance of this quote is rooted in the principles of architectural design and engineering, particularly in the context of fortifications and defensive structures. In ancient times, the thickness of walls played a pivotal role in fortifying cities, castles, and other defensive structures against external threats. A thicker wall not only provided physical protection but also allowed for the movement of defenders and facilitated the deployment of defensive tactics during times of conflict or siege.

From a practical standpoint, the thickness of walls also influenced the distribution of loads and the overall stability of a structure. Thicker walls could better withstand the forces exerted upon them, whether from the weight of the building itself or external factors such as wind, seismic activity, or other environmental pressures. Additionally, thicker walls often allowed for the incorporation of features such as buttresses, reinforcing elements, and defensive mechanisms, further enhancing the defensive capabilities of a structure.

Vitruvius's emphasis on the passage of two armed men serves as a tangible and relatable benchmark for determining the appropriate thickness of walls. This practical guideline aligns with the human-scale approach that Vitruvius championed in his architectural treatise, emphasizing the importance of designing spaces and structures that are functional and accommodating to human needs and activities. The ability for two armed men to pass each other with ease reflects a consideration of human movement and interaction within the built environment, highlighting the intersection of practicality, functionality, and defensive requirements in architectural design.

In modern architectural and engineering practices, the principle of wall thickness continues to be a critical consideration, albeit within different contexts and technological frameworks. While contemporary construction methods and materials have evolved, the fundamental principles underlying the optimal thickness of walls remain relevant. Factors such as building codes, structural requirements, energy efficiency, and the integration of technological systems have expanded the considerations related to wall thickness in contemporary architectural design and construction.

In conclusion, Vitruvius's quote regarding the thickness of walls serves as a timeless reminder of the multifaceted considerations involved in architectural design and construction. Beyond its immediate relevance to fortifications and defensive structures, the concept of wall thickness resonates with broader principles of structural integrity, human-centered design, and the practical requirements of the built environment. As such, it continues to inspire and inform architectural discourse and practice, reflecting the enduring relevance of Vitruvius's insights in the field of architecture and engineering.