Pope Francis has said that Pope Emeritus Benedict XVI’s life of prayer teaches a lesson about doing “theology on his knees”. Francis makes the comments in the preface to a forthcoming book, a collection of writings on the priesthood by the Pope Emeritus. It is one of a series of collections of Benedict's writings which will be published by Ignatius Press. “Every time I have read the works of Joseph Ratzinger/Benedict XVI”, the Pope writes, “it becomes increasingly clear that he has done and is doing “theology on his knees”: on his knees because, even before being a great theologian and teacher of the faith, we see a man who truly believes, who truly prays, you see he is a man who embodies holiness, a man of peace, a man of God.” The Pope writes that this life of prayer, and relationship with Jesus, are the heart of the priest’s life, without which organisational and intellectual skills are useless. Francis goes on to say that since Benedict’s retirement in 2013, his life as Pope Emeritus has given us “one of his greatest lessons of ‘theology on one’s knees’”. The Pope describes Benedict’s life as “constantly immersed in God … like a lover who at every moment is thinking of the beloved”. On June 28 Benedict will return to the Apostolic Palace for the first time since his resignation, in order to celebrate the 65th anniversary of his priestly ordination, which took place on June 28 1951. He will be greeted at the Clementine Hall by Pope Francis. Benedict and Francis have appeared together on a few occasions previously, including the beatification of Paul VI and the opening of the Holy Door at St Peter's. Benedict has described his experience of being ordained as “an initiation into the community of Jesus’ friends, called to be with him and to proclaim his message.”