Super flumina Babylonis illic sedimus et flevimus,
cum recordaremur Sion.
(Offertory of the Mass of the Feria)
There, above the garden, was the Holy Mountain of Sion (Zion), for which the Psalmist in exile had wept. Just a few days before his Passion, the Lord himself had wept again, pouring forth the unfathomable Love which fills His Most Sacred Heart: "Jerusalem, Jerusalem, thou that killest the prophets, and stonest them that are sent unto thee, how often would I have gathered together thy children, as the hen doth gather her chickens under her wings, and thou wouldest not?"
[Regarding the Holy Hour, at every First Thursday of the month, Saint Margaret Mary Alacoque said]: [The Lord] "told me at that time [1674] that, every night from Thursday to Friday, I should wake up, at the time which he appointed, to pray five Paters and five Aves prostrated on the ground, with five acts of adoration which he had taught me, to render him honor in the extreme agony which he suffered at the night of his Passion."[...]
Our Lord himself tells Saint Margaret Mary the spirit in which this exercise should be done [...]:
1. To appease Divine wrath;
2. To demand mercy for sinners;
3. To make reparation for the Apostles' abadonment of Christ.
From the French-Canadian edition of Father Crawley-Boevey's Holy Hour
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A wonderful source for devotions to the Sacred Heart of Our Lord is Catholic Tradition.