[Gustav Mahler, Symphony #8 ]
Cyclic tonality: The music modulates through a series of keys or tonalities, as if in a circle.
Theme: A musical idea, such as a melody, a chord progression, or both, that forms the basis or starting point for a composition or a major section of one. Although the terms "theme" and "subject" are sometimes used interchangeably, "subject" is more traditionally used in speaking of a polyphonic composition such as a fugue.
Motive: A short, incisive, rhythmic and or melodic idea that is sufficiently well defined to retain its identity when elaborated or transformed and combined with other material. It thus lends itself to serving as the basic element from which a complex texture or even a whole composition is created. The term is used rather flexibly but is usually taken to refer to something less than a phrase. A motive may consist of as few as two pitches, or it may be long enough to be seen to consist of smaller elements. Development sections of movements in sonata form are especially likely to be built from motives introduced earlier in the work.
Thematic development: Structural alteration of musical material that has already been stated in the exposition. Development may affect any parameter of a theme; typical examples would include significant modification of pitch contour or rhythm, formal expansion or contraction, textural change, melodic fragmentation, and melodic or contrapuntal combination with other themes. A great deal of thematic development in Romantic music, however, merely restates a theme in different harmonic, timbral, dynamic, registral, and expressive contexts rather than altering its structure.
Musical Analysis: The theoretical or academic study
of musical forms and structures as they are found in specific
musical works.