A Midsummer Night's Dream: Helena Soliloquy

How happy some o'er other some can be!
Through Athens I am thought as fair as she.
But what of that? Demetrius thinks not so;
He will not know what all but he do know:
And as he errs, doting on Hermia's eyes,
So I, admiring of his qualities:
Things base and vile, folding no quantity,
Love can transpose to form and dignity:

At this part of Helena's soliloquy she is saying that she is just as good as Hermia and Demetrius does not see that. He does not know that Helena still loves him but he knows that he is in love with Hermia. He focuses on Hermias beauty when Helena knows that she is an ugly person inside. This is when Helena questions cupid...

Love looks not with the eyes, but with the mind;
And therefore is wing'd Cupid painted blind:
Nor hath Love's mind of any judgement taste;
Wings and no eyes figure unheedy haste:
And therefore is Love said to be a child,
Because in choice he is so oft beguiled.
As waggish boys in game themselves forswear,
So the boy Love is perjured every where:

Helena is questioning why Demetrius is looking only with his eyes and not his mind because he just see's the beauty on the outside of Hermia. Helena feels that Demetrius is being rash with his decision to marry Hermia.

For ere Demetrius look'd on Hermia's eyne,
He hail'd down oaths that he was only mine;
And when this hail some heat from Hermia felt,
So he dissolved, and showers of oaths did melt.

This section talks about how when Helena and Demetrius were together he looked onto Hermia and instantly he gave up every promise, or oath, that he had with Helena and that he was hers. So when he was with Hermia all of his promises melted away and meant nothing.

I will go tell him of fair Hermia's flight:
Then to the wood will he to-morrow night
Pursue her; and for this intelligence
If I have thanks, it is a dear expense:
But herein mean I to enrich my pain,
To have his sight thither and back again.

Here is when Helena decides that she will tell Demetrius about her running off to marry Lysander at his Aunt's house. He will then go into the woods to find her. Helena hopes that Demetrius then will fall in love with her if she follows him into the woods.