How did the Roman Catholic Church decide that there are seven sacraments?

The Roman Catholic Church’s recognition of seven sacraments was a process of theological development rather than a single event. In the 12th century, the theologian and bishop Peter Lombard narrowed the number of sacraments to seven in his influential work, the Four Books of Sentences.12

Lombard’s enumeration—baptism, confirmation, the Eucharist, penance, holy orders, matrimony, and anointing of the sick—was subsequently accepted by prominent theologians and church councils. Specifically, this list was affirmed by St. Thomas Aquinas, the Council of Florence in 1439, and the Council of Trent (1545–63). Through these formal recognitions, the Roman Catholic Church established these seven rites as sacraments instituted by Christ, serving as the essential means for perpetuating the union between God and humankind.13