1. Memento Mori: A warning or reminder of the inevitability of death, esp. a skull or other symbolic object. Later sometimes in weakened use: any grim, ominous, or sobering symbol (dictionary.oed.com).

2. Note the first use of memento mori listed in the OED: 1598 SHAKESPEARE 1 Hen. IV, III. iii. 29, I make as good vse of it as many a man doth of a deaths head, or a memento mori. c1600 Pilgimage to Parnassus II, in Three Parnassus Plays (1949) 106 If I doe not..Ile giue my heade to anie good felowe to make a memento mori of. a1680 EARL OF ROCHESTER Let. from Artemiza in Town in Poems 25 Now scorn'd of all, forsaken, and opprest. She's a Memento mori, to the rest. 1738 G. LILLO Marina I. ii, Thy face is a memento mori for thy own sex. 1798 T. HOLCROFT He's much to Blame III. vii. 47, I never yet saw a mask in the character of a Memento mori. 1850 THACKERAY Pendennis II. xxiii. 229 A great man must keep his heir at his feast like a living memento mori. 1877 W. JONES Finger-ring Lore 372 In the same collection is a ‘memento mori’ ring, of bronze. 1928 L. WOOLF Let. 4 Oct. (1989) 237, I got on quite all right. I started well with a cheerful memento mori. 1985 Times Lit. Suppl. 17 May 544/1 The Socialist Polizeistaat is in itself the largest memento mori for its people.SHAKESPEAREEARL OF ROCHESTERG. LILLOT. HOLCROFT THACKERAYW. JONES

3. Franz Hals, Young Man With a Skull

5. Holbein’s The Ambassadors

6. Caravaggio, St. Jerome Writing (1607)

7. Guercino, Arcadian Shepherds (1618)

8. Pieter Claesz, Vanitas (c. 1625)

9. Pieter Claesz, Vanitas Still Life (c. 1625)