Shakespeare's Sonnets: Thou art as tyrannous, so as thou art

Thou art as tyrannous, so as thou art,As those whose beauties proudly make them cruel,For well thou know'st to my dear doting heartThou art the fairest and most precious jewel.Yet in good faith some say that thee beholdThy face hath not the pow'r to make love groan.To say they err, I dare not be so bold,Although I swear it to my self alone,And to be sure that is not false, I swearA thousand groans but thinking on thy face;One on another's neck do witness bearThy black is fairest in my judgement's place. In nothing art thou black save in thy deeds, And thence this slander, as I think, proceeds.