Swan song for my Feather

With that, I saw two swans of goodly hue,
Come softly swimming down along the Lee ...
So purely white they were,
That even the gentle stream, the which them bare,
Seemed foul to them, and bade his billows spare
To wet their silken feathers, lest they might
Soil their fair plumes with water not so fair
And mar their beauties bright,
That shone as heaven's light,
Against their bridal day, which was not long:
Sweet Thames, run softly, till I end my song.

Spenser Prothalamion (1596) 1. 37