The Holy Hour of Eucharistic Adoration is one of the most ancient and central forms of Catholic prayer — sustained, silent prayer in the real presence of Jesus Christ in the Blessed Sacrament, exposed in a monstrance on the altar. The practice draws directly on the Gospel scene at Gethsemane: Christ asks His apostles, 'Could you not watch one hour with me?' (Matthew 26:40). The 'one hour' is no arbitrary length — it is the explicit request of the Lord on the night of His passion, and the Catholic Holy Hour answers that request directly. The devotional practice of sustained Eucharistic adoration crystallized in the Counter-Reformation and was given particular impetus by the apparitions of the Sacred Heart to St. Margaret Mary Alacoque at Paray-le-Monial (1673-1675); Christ specifically asked Margaret Mary for an hour of reparation in His presence each Thursday night, in remembrance of the Agony in the Garden. The Holy Hour became central to the 'Apostleship of Prayer' (founded 1844) and was preached widely in the twentieth century by Venerable Fulton Sheen (1895-1979), who famously committed to a Holy Hour every day of his priestly life — over 60 years — and credited every grace of his ministry to that hour. Today perpetual Eucharistic adoration chapels operate in thousands of parishes worldwide, staffed by lay volunteers who commit to specific hours through the night and day so that Christ is never left alone in His exposed Sacrament. The Holy Hour is appropriate for: any sustained intercession, especially for healing, conversion, or vocational discernment; reparation for sin (one's own or the world's); spiritual aridity (when prayer feels dry, the presence of the Eucharist sustains the soul even when feelings are absent); preparation for major life decisions; thanksgiving after grace received. It is the prayer Sheen called 'the secret of every priest who became a saint.'