The transition, sometimes referred to as bridge, usually regarded as section of sonata form responsible for modulating from primary to secondary as well as for effecting a structural contrast between two thematic sections. Some sonata-form movements by Mozart have subsidiary and modulatory sections contrast with neighboring thematic sections, such as first movement of Serenade in C Minor, K. 388. However, many movements do not have such well-defined sections. I will explain great variety of functions and structures, accounting for usual strategies Mozart employs. These vary from movements without any apparent section, raising question of location of functions (if, indeed, there are any functions in these movements), such as in first movement of Piano Sonata in C Major, K. 545, to movements gradually ease into new area with a number of subsidiary sections, often combining thematic and transitional such as in first movement of Symphony in D Major (Haffner), no. 35.1 The subject of function and structure usually treated in a general way in most textbooks on musical form or, in more detail, in studies of sonata form, of classical period music, or of Mozart's music. I will summarize here one author's views of transitions in order to indicate typical sorts of statements made on this topic; reader will find a summary of various other views of transitions in appendix to present paper. Green (1979:195) categorizes possible functions of sonata-form as follows: 1. Modulation to new 2. Development of a motive or motives from first theme 3. Introduction of a mood which contrasts with of both first and second themes 4. Introduction of new material which contrasts thematically with both first and second theme 5. Preparation of listener for second theme by gradual change from one mood to another 6. Preparation of listener for second theme by anticipation of its characteristic rhythm or melodic motive Like most textbook summaries of transitions (or other aspects of form), this one not terribly useful because it so general. Green admits no single can perform all these functions, and no one function an indispensable feature of any transition (p. 195). He also notes transitions may not fully modulate to new or may not modulate at all, and there may not even be a (pp. 195-197). Green's discussion of modulation more detailed, especially in his analyses of various transitions. He concludes most transitions have three phases: first, that part before modulation begins to set in, second, the deflection away from tonic by introduction of leading tone, and third is marked by leading tone to V (i.e., #4) of new key (p. 190). Melodically, he classifies transitions as either dependent, if they are based on first theme material, or independent, if they are not. He uses Mozart's Piano Sonata K. 333 for discussion of these points, a discussion I will refer to below. Briefly, some of Mozart's transitions do have some of functions Green notes above, although there are other possible functions they may have, as I will discuss. Only a few of Mozart's transitions have all three of Green's harmonic phases; many have only first two, some have only second, and some have only second and third. In general, remarks on transitions by Green and others (as noted in appendix) are often useful, but there are other kinds of things to be said about transitions will lead to a more complete picture of their functions and structures. With respect to Mozart's works, I will describe patterning at various levels with aim of determining unique features and structures of transitions, and how functions operate in sonata form, even in absence of a distinct section. …
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