The 'expression theory' of music proposes that the primary purpose of music is to express emotions, feelings, and ideas through musical sounds.

The 'absolute music' theory suggests that music is an autonomous art form that exists for its own sake, without any need for external references or programs.

In his 'Critique of Judgment,' Immanuel Kant proposed that music has the unique ability to bypass the intellect and directly access the realm of the transcendental, evoking a sense of awe and wonder.

Catharsis, a term derived from ancient Greek drama, refers to the emotional release and purification experienced by listeners when engaging with music.

Hector Berlioz was a prominent composer of the Romantic era who championed the concept of 'program music,' creating works like 'Symphonie Fantastique' that vividly depict specific narratives and emotions.

Musical rhetoric refers to the use of musical elements, such as melody, harmony, and rhythm, to convey specific emotions, ideas, or narratives, akin to the use of rhetorical devices in language.

Plato, in his 'Republic,' proposed that music has a profound impact on the moral development of individuals and the harmony of society, advocating for the careful selection and regulation of music in his ideal state.

Sacred music encompasses music specifically composed for religious purposes, often associated with rituals, ceremonies, and worship in various religious traditions.

Richard Wagner is renowned for his innovative use of leitmotifs in his operas, where recurring musical themes are associated with specific characters, objects, or ideas, enhancing the dramatic impact of the narrative.

Ethnomusicology is the study of music in its cultural context, exploring the relationship between music and various aspects of culture, such as ethnicity, geography, and social practices.

John Dewey, in his work 'Art as Experience,' proposed that music has the unique capacity to transcend cultural and linguistic differences, fostering a sense of shared humanity and understanding among people from diverse backgrounds.

Film score refers to the original music composed specifically for a film, designed to enhance the emotional impact and atmosphere of the visual narrative.

Philip Glass is a prominent minimalist composer known for his repetitive patterns, steady rhythms, and use of simple harmonies, creating a hypnotic and meditative effect in his music.

Protest music refers to music that is explicitly created to express political or social dissent, often addressing issues such as injustice, inequality, and oppression.

Arthur Schopenhauer, in his work 'The World as Will and Representation,' proposed that music has a metaphysical dimension, capable of revealing the underlying essence of reality and providing a glimpse into the realm of the divine.