beáti mórtui qui in Dómino moriúntur.
On All Souls Day, or the 'Commemoration of all the Faith Departed', we pray at Mass for those who have gone before that they may be released from the pains of Purgatory, identical in suffering to the pains of hell, though not eternal in duration.
The Holy Souls have hope and confidence of entering into the Beatific Vision when they are cleansed of sin. Of course, the dead are recalled within every Mass but especially on All Souls Day.