You're my devil, you're my angel
You're my heaven, you're my hell
You're my now, you're my forever
You're my freedom, you're my jail
You're my lies, you're my truth

from Kanye West – Lost In The World Lyrics on Rap Genius

Meaning

Each line contains a binary contrasts, eg. good and evil. Ye is saying the girl he is with is the best yet worst thing to ever happen to him, which shows the impossibility of the relationship. He explains that this “girl” is his everything through contrasting dualities. In order for one to hold meaning, the other must exist, and he becomes bound to her in both ways.

This “girl” could actually symbolize his career as a hip-hop superstar, just as he used a girl to symbolise Chicago in Homecoming.

In recent interviews, Kanye has admitted that this verse was for Kim.
http://www.youtube.com/watch?v=5TBHmMonV0s#t=09m50s

Also notice the chiasmus, which is very rare in hiphop!

For those who don’t know, a chiasmus is the figure of speech in which two or more clauses are related to each other through a reversal of structures in order to make a larger point. In other words, the sequence of the words make up an “X” or an “ABBA” structure.

In this line, the chiasme consists of “good” and “bad” things:

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