In Robert Frost's letter to Louis Untermeyer (1 January 1916):
"A poem...begins as a lump in the throat, a sense of wrong, a homesickness, a lovesickness. It is a reaching-out toward expression; an effort to find fulfillment. A complete poem is one where an emotion finds the thought and the thought finds the words."
Source: http://en.wikiquote.org/wiki/Robert_Frost 27 March 2013.