The aim of this article is to enhance knowledge of and to encourage further research into two areas not traditionally the subject of socio-legal research, namely, the work of Karl Renner and the English law of mortgage, for three reasons. First, an account of them supports the proposition that a true understanding of law requires knowledge of its origins, content, and function. Second, Renner's theory can contribute significantly to our understanding of law by offering an alternative to the polarized debate between legal autopoiesis and other sociological conceptions of law. Third, it has much to tell us about the relationship between legal and social change. In particular, Renner's work suggests that those seeking legal reform should look ...