Could you not watch one hour with me?
Matthew xxvi. 40

After the Holy Sacrifice of the Mass, one of the greatest ways to show devotion to our Blessed Lord is to adore Him in His True Presence in the Most Blessed Sacrament. Though the widespread presence of perpetual adoration chapels for the laity is a new development, devotion to Our Lord in the Most Blessed Sacrament goes back centuries. According to the late Father John Hardon, “It is authentic Catholic doctrine and it rests on the unchangeable truth of our revealed faith.”

The Manual devotes 9 pages to devotions to be used during a visit to the Most Blessed Sacrament. It also contains a very good history of the development of the Forty Hours' Adoration, which was the most common expression of Eucharistic Adoration when the Manual was written.