Imperceptibly.

Homer, The Song of the Lark, 1876

The stream swirls. The wind moans in
The pines. Gray rats scurry over
Broken tiles. What prince, long ago,
Built this palace, standing in
Ruins beside the cliffs? There are
Green ghost fires in the black rooms.
The shattered pavements are all
Washed away. Ten thousand organ
Pipes whistle and roar. The storm
Scatters the red autumn leaves.
His dancing girls are yellow dust.
Their painted cheeks have crumbled
Away. His gold chariots
And courtiers are gone. Only
A stone horse is left of his
Glory. I sit on the grass and
Start a poem, but the pathos of
It overcomes me. The future
Slips imperceptibly away.
Who can say what the years will bring?

Tu Fu