A subitanea morte, libera nos, Domine …
“from a death that is sudden and unprepared for, deliver us, o Lord.”
To be taken away suddenly, without being able to make oneself ready, without having had time to prepare – this is the supreme danger from which man wants to be saved. He wants to be alert as he sets out on that final journey. He wants dying to be his own action. If one were to forumlate today a Litany of the Unbelievers the petition would, no doubt, be just the opposite: a sudden and unprovided death grant to us, o Lord. [wanting death to] happen at a stroke, and leave no time for reflection or suffering.
Eschatology: Death and Eternal Life. Joseph Ratzinger. p. 71.
read all of Ratzinger’s reflection here