William Shakespeare: I grant thou wert not married to my Muse

I grant thou wert not married to my Muse,
And therefore mayst without attaint o'erlook
The dedicated words which writers use
Of their fair subject, blessing every book.
Thou art as fair in knowledge as in hue,
Finding thy worth a limit past my praise;
And therefore art enforced to seek anew
Some fresher stamp of the time-bettering days.
And do so, love; yet when they have devis'd,
What strained touches rhetoric can lend,
Thou truly fair, wert truly sympathiz'd
In true plain words, by thy true-telling friend;
And their gross painting might be better us'd
Where cheeks need blood; in thee it is abus'd.