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.
In plain English
You were never bound to me as my muse, so you're free to ignore the flowery language that other writers heap on their subjects—all that blessing and praise in every dedicatory poem. You're intelligent and beautiful both, and your worth exceeds anything I could say about you.
That's why you've turned to seek out fresher, fancier writers—ones who use all the rhetorical tricks of the moment to glorify you. Go ahead, love. But here's the truth: when those poets throw their strained language at you, you'd only be truly understood by someone like me, your honest friend who speaks plainly. Their elaborate painting belongs somewhere else—on pale cheeks that need color. On your face, all that artifice is just wasted.
The sonnet's core move: the speaker concedes the rival poet's point (the beloved is too magnificent for simple praise), but uses that concession to argue that *true* understanding doesn't need ornament. Plain truth trumps rhetorical display.