Midsummer Night's Dream - Helena soliloquy translation help?

Question:I'm translating it for my own reference, but am having trouble with these two lines. It is part of Helena's soliloquy in the play, where she is wondering why Demetrius dosen't love her and decides to tell him of Hermia and Lysander's plan to run away. Here's the paragraph/s the line is in (I only need to know the translation for the lines in capitals)

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.

As waggish boys in games themselves forswear,
So the boy love is perjured everywhere.
FOR ERE DEMETRIUS LOOKED ON HERMIA'S EYNE,
He hailed down oaths that he was only mine.

Please only answer if you're sure. Thannnks xx

Best Answer - Chosen by Asker: I'm translating it for my own reference, but am having trouble with these two lines. It is part of Helena's soliloquy in the play, where she is wondering why Demetrius dosen't love her and decides to tell him of Hermia and Lysander's plan to run away. Here's the paragraph/s the line is in (I only need to know the translation for the lines in capitals)

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.

As waggish boys in games themselves forswear,
So the boy love is perjured everywhere.
FOR ERE DEMETRIUS LOOKED ON HERMIA'S EYNE,
He hailed down oaths that he was only mine.

Please only answer if you're sure. Thannnks xx

For the first line:
The word "know" is being used as a synonym for "see" or "realize", so:
"will not know" = "does not see"
"all but he" = "everyone else"
So, the 'translation' would be "He can't see what everyone else sees." Even though she is every bit as beautiful as Hermia, Demetrius is so focused on his new love that he cannot see Helena's beauty.

For the second line:
"ere" = before
"eyne" = eye
Therefore the translation would be, "Before Demetrius looked upon Hermia's eyes..." This echoes the earlier line, "And as he errs, doting on Hermia's eyes."

The theme of "eyes" and "seeing" runs not only through the speech, but through the entire play. AMSND is all about how we perceive those we love, and how our love for them blinds us. This is such a great piece--Helena pretty much sums up the entire message of the show right here.