Indocili numero, cum grave mollit opus.
Cantat et innitens limosæ pronus arenæ,
Adverso tardam qui vehit amne ratem;
Qui refert pariter lentos ad pectora remos,
In numerum pulsâ brachia versat aquâ.
…
Cantantis pariter, pariter data pensa trahentis
Fallitur ancillæ, decipiturque labor.”
Ovid, de Tristibus, Eleg. lib. i.
And, in our own literature, the great poet of human nature, Shakspeare: