Thou art as tiranous, so as thou art,
As those whose beauties proudly make them cruell;
For well thou know'st to my deare doting hart
Thou art the fairest and most precious Jewell.
Yet in good faith some say that thee behold,
Thy face hath not the power to make love groan;
To say they erre, I dare not be so bold,
Although I sweare it to my selfe alone.
And to be sure that is not false I sweare
A thousand grones but thinking on thy face,
One on anothers necke do witnesse beare
Thy blacke is fairest in my judgements place.
In nothing art thou blacke save in thy deeds,
And thence this slaunder as I thinke proceeds.
The first quatrain establishes that the poet is in love with a woman who is acting tyrannically, as tyrannically as a beautiful woman acts, but that she only gets away with it because of the poet's tender feelings for her, his 'doting on her'. It is tempting to hear the typical Irishism in the first line: 'you are as tyrannical, so you are, as ....'
In the second quatrain the poet establishes that others do not think her so beautiful, and he comments that he dare not contradict them, though he silently retains his own opinion of her.
The third quatrain insists that his point of view is truly how he feels: 'a thousand grones' attest to the fact, 'grones' which arrive one after the other (one on anothers neck). He insists: her black is fairest.
The reflective final couplet expresses the thought that it is only because of her deeds that she is not thought beautiful by others, the bad opinion that they express of her proceeds from this, not from her looks..
A couple of questions occur with regard to this sonnet. Firstly, why does he not dare to express his opinion that the woman is fair? One can speculate that the persons giving the opposite opinion are Shakespeare's social superiors. He would not 'be so bold' as to contradict them. Secondly, the line 'In nothing art thou black save in thy deeds' clearly contradicts the idea that this woman is the dark lady, who has already been described as having 'raven black' eyes. This woman, it appears, is black because of her moral turpitude. But, though he observes it, there is no condemnation from the poet of this fact.