In 1882, Jesus appeared to a young Italian visionary named Luisa Piccarreta and showed her the last 24 hours of His Passion, starting with the moment He said good-bye to His Mother (just before the Last Supper) and ending with the moment He was buried. Jesus then asked Luisa to meditate on these hours.
After Luisa had been living the Hours of His Passion for over thirty years, Saint Hannibal told her to write the revelations in a book. Saint Hannibal was greatly moved by the book and printed it with a Preface that he wrote himself.
In the Preface to the 24 Hours of the Passion, St. Hannibal recalled Christ’s promise of protection to those who pray the Hours, saying: “If on account of only one soul doing these hours, Jesus would spare a city of chastisements and would give grace to as many souls as there are words of these sorrowful hours, how many graces might a community [or any group of individuals] expect to receive?”
On May 16, 1917, Jesus confirmed this when He told Luisa, “These Hours are the order of the Universe; they put Heaven and earth in harmony, and restrain Me from sending the world to ruin..."
A Community Clock is a group of 24 people praying the 24-Hours together. Each person is assigned one of the 24 hours (for example, the 6 PM hour or the 4 AM hour). With each hour of the day assigned, the members of the group collectively complete the hours together. If you complete the hours as a group and want to continue the devotion as a perpetual clock, it might be helpful to assign each person an initial time and then rotate hours. That way, the burden of the nighttime hours is shared.