When a rapper jumps on a beat, he adds his own rhythm. Sometimes you stay in the pocket of the beat and just let the rhymes land on the square so that the beat and flow become one. But sometimes the flow chops up the beat, breaks the beat into smaller units, forces in multiple syllables and repeated sounds and internal rhymes, or hangs a drunken leg over the last bap and keeps going, sneaks out of that bitch.
This is from Jay-Z’s fantastic new book Decoded. Because I’m lazy, I stole that quote from Kelefa Sanneh’s excellent review here, which, in turn, I stole from Jay Smooth’s twitter. Still. Read the book. It’s really good.