John Williams is a movie legend who frequently uses specific 'instrumental colors' to define characters. For the 'Harry Potter' series, he chose the celesta to play the opening notes of 'Hedwig’s Theme.' The celesta is a keyboard instrument that looks like a small piano but strikes metal plates instead of strings, producing a bell-like, twinkling sound. Williams felt this 'music box' quality perfectly captured the wonder and mystery of the wizarding world. The instrument’s delicate, ethereal tone became instantly iconic, and now, those first few notes on the celesta are globally recognized as the 'sound of magic.' It is a prime example of how a relatively obscure instrument can become a central pillar of a multi-billion dollar movie legend.