The relationship between theme music and theme is: theme refers to the content that is complete, formed and often able to clearly reflect the character of the music. Generally, it must be at least a phrase or even a section. A musical idea refers to any form of musical material thought up by the composer. It can be large or small. The book mentions "single musical idea" because a piece of music generally consists of one musical idea through "start, succession, transition, and transition." It was developed through the process of "integration". As the music develops, themes emerge, and it can also be seen as forming a larger music.