The Cistercian monasteries that sprang up throughout Europe in the 12th century exemplified a way of communal life guided by the principles of self-sufficiency, simplicity, and brotherhood. The Cistercians’ intention in creating these exemplary “small worlds” set apart from the wider world plagued by disorder was essentially spiritual. Nevertheless, the form of communal life they organized and put into practice constitutes a sort of historical prototype for later utopian experiments that would seek to promote, through example and small-scale implementation, a model of strong sustainability. This is why the early Cistercian experience serves as a source of inspiration for contemporary attempts to break away from a socioeconomic system dominated by growth. In particular, the Cistercian Rule offers a normative framework for envisioning the legal structure of a world committed to degrowth.