Analysis of Sonnet XIII: Letters and Lines

To the Shadow

Letters and lines we see are soon defac'd,
Metals do waste and fret with canker's rust,
The diamond shall once consume to dust,
And freshest colors with foul stains disgrac'd;
Paper and ink can paint but naked words,
To write with blood of force offends the sight;
And if with tears I find them all too light,
And sighs and signs a silly hope affotds,
O sweetest shadow, how thou serv'st my turn,
Which still shalt be, as long as there is sun,
Nor, whilst the world is, never shalt be done,
Whilst moon shall shine or any fire shall burn;
That everything whence shadow doth proceed
May in my shadow my love's story read.