[esskay]

There's a 5th as well if we're counting them(though I imagine the methods to writing a song our infinite) But jamming with other musicians. I mean not with writing the lyrics but I've came home and wrote many a song from an idea that would have never happened if it wasn't for spontaneous jamming. Especially if you have a verse or chorus that you don't know what to do with. Jamming on it with friends explores the possibilities that only another human player with his or her own style could bring to it. But I'd say try not to think of it as a math formula. It's giving me writers block as I type it. But thinking in formulas really closes off any creativity at least for me. To each their own I suppose.