He was born on 7 March 1922 and entered the Franciscans in 1937 at the age of 15. He made his solemn profession on 31 December 1943, and was ordained on 4 May 1946. He taught dogmatic theology in Tuscany until 1963. At the Second Vatican Council he was a consultor to the Theological Preparatory Commission and collaborated in writing "Dei Verbum" and "Lumen Gentium". He was a professor of fundamental and dogmatic theology in Rome from 1964 to 1991.
He was not consecrated as a bishop upon being made a Cardinal, having asked the Holy Father to be dispensed from this obligation.
Pope Benedict XVI made him a Cardinal on 24 November 2007, after he had already reached his 80th birthday.