O misery! misery! Time eats our lives,
And that dark Enemy who gnaws our hearts
Grows by the blood he sucks from us, and thrives.

[Ô douleur ! ô douleur ! Le Temps mange la vie,
Et l’obscur Ennemi qui nous ronge le cœur
Du sang que nous perdons croît et se fortifie!]

Charles Baudelaire (1821-1867) French poet, essayist, art critic

Les Fleurs du Mal [The Flowers of Evil], # 10 “L’Ennemi [The Enemy],” st. 4 (1857) [tr. Squire (1909)]
    (Source)

Also in 1861, 1868 eds. (Source (French)). Alternate translations:

Oh misery! -- Time devours our lives,
And the enemy black, which consumeth our hearts
On the blood of our bodies, increases and thrives!
[tr. Scott (1909)]

o grief! o grief! time eats away our lives,
and the dark Enemy gnawing at our hearts
sucks from our blood the strength whereon he thrives!
[tr. Shanks (1931)]

Oh, anguish, anguish! Time eats up all things alive;
And that unseen, dark Enemy, upon the spilled
Bright blood we could not spare, battens, and is fulfilled.
[tr. Millay (1936)]

Time swallows up our life, O ruthless rigour!
And the dark foe that nibbles our heart's root,
Grows on our blood the stronger and the bigger!
[tr. Campbell (1952)]

Alas! Alas! Time eats away our lives,
And the hidden Enemy who gnaws at our hearts
Grows by drawing strength from the blood we lose!
[tr. Aggeler (1954)]

Time and nature sluice away our lives.
A virus eats the heart out of our sides,
digs in and multiplies on our lost blood.
[tr. Lowell (1963), "The Ruined Garden"]

О grief! О grief! Time eats away life,
And the dark Enemy who gnaws the heart
Grows and thrives on the blood we lose.
[tr. Fowlie (1964)]

Time consumes existence pain by pain,
and the hidden enemy that gnaws our heart
feeds on the blood we lose, and flourishes!
[tr. Howard (1982)]

I cry! I cry! Life feeds the seasons' maw
And that dark Enemy who gnaws our hearts
Battens on blood that drips into his jaws!
[tr. McGowan (1993)]

Time eats at life: no wonder we despair.
Our enemy feeds on the blood we lose.
He gnaws our heart, and look how strong he grows.
[tr. Lerner (1999)]

O pain! pain! Time devours life and the dark Enemy that gnaws our heart grows, and grows strong, from the blood we let.
[tr. Waldrop (2006)]