to lowest pitch of abject fortune thou art fallen

[Jackson6612]

<to lowest pitch of abject fortune thou art fallen — John Milton

4pitch (noun):
4 a : the relative level, intensity, or extent of some quality or state <tensions rose to a feverish pitch>
[M-W's Col. Dic.]

Which definition of "pitch" fits here, the 4th one?
pitch
http://www.merriam-webster.com/dictionary/fortune

What would "art" mean here in this context?

Please help.

Context:
http://books.google.com/books?id=Sxj0I6qilcwC&pg=PA360&dq=to+lowest+pitch+of+abject+fortune+thou+art+fallen&hl=en&ei=bMtITNHcMsTIcbig4M8M&sa=X&oi=book_result&ct=result&resnum=2&ved=0CCoQ6AEwAQ#v=onepage&q=to%20lowest%20pitch%20of%20abject%20fortune%20thou%20art%20fallen&f=false

[Mister Micawber]

'Thou art' = 'you are'.
You have linked to 'fortune', not 'pitch', but yes, 'level': relative point, position, or degree: 'a high pitch of excitement'.
_________________
Native English teacher at Mister Micawber's

[Jackson6612]

Thanks for the clarification, Mr. Micawber.

Sorry for the wrong linking. I used a wrong heading 'pitch', actually I wanted to ask about 'fortune'. Which definition of "fortune" fits here best in your opinion, the 4th one?

fortune
http://www.merriam-webster.com/dictionary/fortune

[Mister Micawber]

Yes, #4.
_________________
Native English teacher at Mister Micawber's

[Jackson6612]

Thank you.