A Sonnet is a moment's monument,
Memorial from the Soul's eternity
To one dead deathless hour. Look that it be,
Whether for lustral rite or dire portent,
Of its own arduous fulness reverent:
Carve it in ivory or in ebony,
As Day or Night may rule; and let Time see
Its flowering crest impearl'd and orient.

A Sonnet is a coin: its face reveals
The soul,--its converse, to what Power 'tis due: --
Whether for tribute to the august appeals
Of Life, or dower in Love's high retinue,
It serve; or, 'mid the dark wharf's cavernous breath,
In Charon's palm it pay the toll to Death.

Dante Gabriel Rossetti

http://www.poemhunter.com/poem/the-house-of-life-the-sonnet/