Many people assume it was the actors and actresses that made it such a hit.
But, even though the acting was far above average, without the beautiful music, breathtaking scenery, and amazing special effects, this masterpiece would have sunk. Music can usually express emotions much better than actors and actress. It would not be moving or frightening. It would be tedious, just waiting for boring, silent scenes to get over with. Sometimes strong emotions just can not be put into words, so music expresses them instead.