Petrarch, Secretum 1.1:
Augustine: What are you doing, little man? Why do you sleep? What are you waiting for? Have you become so forgetful of your own misery? Or do you not remember that you are mortal?
Francesco: I remember, to be sure, and that thought never comes upon me without a certain horror.
Augustine: Would that you remember as you say you do and consulted your own interest! Indeed, then you would have freed me from a lot of labor, since it is indeed true that nothing is more effective for condemning the temptations of this life and composing the mind to endure the many tempests of this world than the recollection of one’s own misery and a constant meditation upon death. Yet, it should not come upon you lightly or superficially – it should settle into your bones and marrow.
Augustinus: Quid agis, homuncio? quid somnias? quid expectas? miseriarum ne tuarum sic prorsus oblitus es? An non te mortalem esse meministi?
Francescus: Memini equidem nec unquam sine horrore quodam cogitatio illa subit animum.
Augustinus: Utinam meminisses, ut dicis, et tibi consuluisses! etenim et multum michi negotii remisisses, cum sit profecto verissimum ad contemnendas vite huius illecebras componendumque inter tot mundi procellas animum nichil efficacius reperiri quam memoriam proprie miserie et meditationem mortis assiduam; modo non leviter, aut superficietenus serpat, sed in ossibus ipsis ac medullis insideat.