Bernard of Clairvaux was a Cistercian abbot, reformer, preacher, and theologian whose influence shaped twelfth-century Europe spiritually, politically, and intellectually. Born near Dijon into a Burgundian noble family, he entered the Cistercian monastery of Cîteaux in 1112 and soon became the founding abbot of Clairvaux (1115), one of the most important daughter houses of the order.

Bernard’s spirituality emphasised interior conversion, humility, and loving union with Christ. His sermons on the Song of Songs articulated a profoundly affective theology in which the soul’s relationship with God was described in nuptial language. For Bernard, true authority rested not in domination but in conformity to divine charity.

He was also a formidable public figure. Bernard intervened in ecclesiastical disputes, advised kings and popes, and played a decisive role in resolving the papal schism of 1130 in favour of Innocent II. His advocacy helped secure recognition of the Knights Templar at the Council of Troyes (1129), and in 1146 he preached the Second Crusade at Vézelay, urging Christendom to military action — a campaign whose ultimate failure did not diminish his reputation in his lifetime.

Bernard’s theology of authority was deeply Augustinian. In works such as De consideratione (addressed to Pope Eugene III, a former Cistercian monk), he warned against the spiritual dangers of power exercised without humility. Authority, he insisted, must be pastoral and ordered toward salvation. His critique of clerical luxury and moral laxity reinforced the Cistercian commitment to simplicity in architecture, liturgy, and monastic life.

Canonised in 1174 and later declared a Doctor of the Church (1830), Bernard stands at the intersection of monastic reform, ecclesiastical politics, and devotional theology. His legacy shaped both spiritual literature and the broader conception of Christian governance in the twelfth century.