Among the many noteworthy biographical details of Pope Leo XIV, one is his generational place. I do not merely mean that the first American pope is also the first Baby Boomer pope, born in 1955. I mean where he is situated in Church history relative to the Second Vatican Council.
Vatican II, which revolutionized the Catholic liturgy and many other pastoral matters, ran from 1962 to 1965. It was called by Pope John XXIII, who died in June 1963, and its work was completed under Pope Paul VI, who headed the Church until 1978. For better and worse, it brought the Church into the modern world.
Popes John Paul II and Benedict XVI were both active participants in the council. Pope Francis entered the Jesuit novitiate in 1958 and was ordained a priest in 1969, so Vatican II shaped his immediate formation as a priest. But Leo XIV was ten years old when Vatican II concluded. He is the first pope who was not already a clergyman during Vatican II. If his papacy lasts into his mid-80s, it is very likely that he will also be the last pope with a living memory of the pre–Vatican II Catholic Church. It will fall to him to carry whatever he deems worthy of remembrance of that old, faithful church forward into the living practice of the 21st century.