Origin of phrase...Help please!

Posted by Kari on January 05, 2001

Last year, my Brit. Lit. teacher told us that Sara Teasdale coined the phrase "Burning a candle at both ends", but he read us this poem by Enda St. Vincent Millay:
"My candle's burning at both ends/It will not last the night./But Oh my foes, and Ah my friends/It sheds a lovely light."
I'm wondering if he got confused, pleas help.