Berryman's major poetic breakthrough came after the first volume of "The Dream Songs", "77 Dream Songs", in 1964. The dream song form consists of short, 18-line lyric poems in three stanzas. They are in free verse, with some stanzas containing irregular rhyme. "77 Dream Songs" (and its sequel "His Toy, His Dream, His Rest") centers on a character named Henry who bears a striking resemblance to Berryman, but Berryman was careful to make sure his readers realized that Henry was a fictional version of himself (or a literary alter ego). In an interview, Berryman said, "Henry does resemble me, and I resemble Henry; but on the other hand I am not Henry. You know, I pay income tax; Henry pays no income tax. And bats come over and they stall in my hair — and fuck them, I'm not Henry; Henry doesn't have any bats."