How did Peter Lombard influence the Western Christian list of seven sacraments?

In the 12th century, the theologian and bishop Peter Lombard played a pivotal role in standardizing the Western Christian understanding of sacraments. In his influential work, the Four Books of Sentences, he narrowed the diverse list of rites to seven: baptism, confirmation, the Eucharist, penance, holy orders, matrimony, and extreme unction.12

Beyond merely listing them, Lombard refined the theological definition of a sacrament. He argued that a sacrament is not only a visible sign of invisible grace but also the cause of the grace it signifies. This sevenfold enumeration became the standard for the Western church, receiving formal acceptance from St. Thomas Aquinas, the Council of Florence, and the Council of Trent, ultimately cementing these rites as the core sacraments of the Roman Catholic Church.21