Perhaps his unique contribution to the renewal of the liturgy is his greatest legacy of all. All his life, he promoted a reform of liturgy according to the spirit and the letter of Vatican II. How pivotal Benedict XVI saw the reform of the liturgy for the life and mission of the Church can be seen from his decision to publish as the
first Volume of his Collected Works that on the Theology of the Liturgy (which is Volume 10 in the series).