核心畫面

You can think of rocker as the thing that does the rocking. Picture the two curved strips of wood under an old chair: only a small part of each curve touches the floor, so the chair can never quite stand still, and one light push sets it going back and forth. Rock means to move gently to and fro, and -er names the one that does it. From that one picture the word grows in two directions: things that really do tip back and forth — the curved strip, the whole chair, the wall switch that tips like a tiny seesaw — and the people and songs that belong to rock music, where the same movement lives in the sound.