My candle burns at both ends;
   It will not last the night;
But ah, my foes, and oh, my friends—
   It gives a lovely light!
What is the  “it”  in  “it gives a lovely light”?  is  “it”  really the candle? It may be life, or her passions- it is up to the reader to decide. 
 Her passion (for writing? life?) may burn itself out early, but it’ll be beautiful while it lasts. 
 Notice the catchy vowel cluster in  “ah, my foes, and oh, my friends” - when you say only the vowels together, it sounds like  “AH-OH-OH-EH” . This may be telling us that Friends and Foes are really similar after all. 
 “These violent delights have violent ends And in their triumph die, like fire and powder, Which as they kiss consume…” ( Romeo and Juliet , Act 2, Scene 6 ) 
 Essentially – it isn’t going to work out long term, but things are nice in the moment.
First Fig My candle burns at both ends...