Virgil's melancholy

... everything, by nature's law
Tends to the worse, slips ever backward, backward
As with a man, who scarce propels his boat
Against the stream: if once his arms relax
The current sweeps it headlong down the rapids

Virgil, Georgics, bk I-199

Twice in the year, men gather the honey harvest
First when Taygete the Pleiad shows
Her comely face to the world, and with her foot
Has spurned the streams of Ocean; and again
When the same star, fleeing the rainy sign
Of the Fish, more sadly hastens down the sky
Into the wintry waves

Ibid, bk IV, 231-5