"The only way to get a thing done is to start to do it, then keep on doing it, and finally you'll finish it. . ."
Criticizing the members of the Harlem Renaissance for not being productive with their fame, Hughes offers a solution: do what you say you're going to do. He is writing this book out of frustration with unfulfilled promises. The "New Negro" movement was supposed to be a season of political, social, and economic change for African Americans, but instead the members of the movement became interested in social acclaim and money. They became celebrities. Hughes is chastising the people for not actually doing anything.
"For poems are like rainbows; they escape you quickly."
Hughes is relating his artistic history here. He always had considered himself a poet. Now he realizes that he lost the vast majority of his poetry to memory, or more accurately the limitations of language. As quickly as he can think of a line, he cannot record the line in written form, just the same as you can never find the end of a rainbow.
"Then it was that books began to happen to me, and I began to believe in nothing but books and the wonderful world in books -- where if people suffered, they suffered in beautiful language, not in monosyllables as we did in Kansas."
Hughes, the young poet, was fascinated by the elaborate grandeur of language he read in books. He loved the way books could say something ordinary in the most elegant way that you could barely recognize the concept. When he started reading books seriously, he started losing himself to the books. He became disillusioned with the utilitarian approach to language which he observed all around him. All of a sudden, his surroundings didn't match his experience.
"You see, books had been happening to me."
By this point in the book, Hughes has experienced enough to come back to his original fascination with books. He has accepted the quest and can acknowledge that books were his guiding force. He had allowed himself to play a third party role in his own life, as if he were a character in somebody else's novel.
