“Heart Songs” seems to have two meanings, and the way they don’t get along showcases a dilemma. The first meaning is as obvious as it is harmless: Rivers is paying tribute to the songs and artists that have affected him in one way or another throughout his life. The second meaning is a little more delicate, and feels a bit like eavesdropping since it’s probably unintentional. It sounds like someone searching for his muse. In the bridge, Rivers climactically recalls listening to Nirvana’s Nevermind, and what a breakthrough that album …