Aelred of Rievaulx (1110–1167), a Cistercian monk and abbot, wrote De institutione inclusarum sometime between 1160 and 1165 at the request of a recluse he called his sister. De institutione is a practical ascetic guide and contemplative work written with the needs of female recluses in mind, focusing on topics from the temptation of idle gossip, the mentorship of male priests, and the education of young children to devotional practice. Divided into three thematic sections—the inner person, the outer person, and a threefold meditation—the work became foundational to both the emerging popular affective and the anchoritic traditions of the late Middle Ages.