With wavering steps does fickle fortune stray,
Nowhere she finds a firm and fixed abode;
But now all smiles, and now again all frowns,
She's constant only in inconstancy.
Time itself flows on with constant motion, just like a river: for no more than a river can the fleeting hour stand still. As wave is driven on by wave, and, itself pursued, pursues the one before, so the moments of time at once flee and follow, and are ever new.