The tradition of 40 Hours devotion dates back to at least the 16th century. This custom, in which the Blessed Sacrament is exposed for forty consecutive hours for all to adore, was promoted by numerous saints, including Saint John Neumann in the United States.

This 40 Hours booklet is an essential companion for parishioners participating in this devotion. Public and personal devotions for Eucharistic adoration, a history of the devotion, prayers before the Blessed Sacrament, and reflections on the Eucharist are included.

The 40 Hours devotion provides the faithful an opportunity for a personal encounter with Jesus, truly present in the consecrated host in the monstrance. Saint Alphonsus Liguori wrote, "Of all devotions, that of adoring Jesus in the Blessed Sacrament is the greatest after the sacraments, the one dearest to God and the one most helpful to us."