In both his article Property as the Law of Things and his prior work, Professor Henry Smith has revitalized property law theory by emphasizing the architectural role that property plays in private law and the ways in which modular property rights reduce information costs and promote both property use and transfer. I applaud Smith's insistence that we focus on the systemic nature of property rights and the benefits of bundled entitlements. At the same time, it is important to understand the limitations of Smith's analysis. Property law goes beyond managing the complexity of human interaction. Property not only presents a coordination problem but also a constitutional problem. Many issues fundamental to property law systems require attention ...