When talking about tonal music, we sometimes tend to take for granted the idea that the tonic should always be clearly established either at the beginning or the end. However, there are composers who sometimes deviate from the normal path by creating different types of riddles or tonal enigmas in their works. Some of these riddles can be solved later on as the piece progresses; yet others may need to bexplained with the help of some external references. This thesis examines three such examples, each of which poses its unique enigma. The second movement of Bruckner's Symphony No. 1 presents a dualism between Ab and F (paralleled by their dominants Eb and C); Brahms's Alto Rhapsody involves an enormous auxiliary cadence spanning 2/3 of the piece and a seemingly plagal cadence which turns out to be authentic with the V suppressed; and eventually, Grieg's setting of Dereinst, dereinst, Gedanke mein provides a paradoxical ending which may be understood as incorporating the composer's attitude towards the text.

This dissertation explores the use of topics for dramatic purposes in Mozart's Così fan tutte. The five analytical chapters are organized around a central question: how do pastoral and fanfare topics shape the plot of Così fan tutte? Chapter 2 highlights the role topics and tropes play in emplacing and nuancing emergent meaning in the Così fan tutte motto. Chapter 3 examines transformative topical tropes in "Ah guarda, sorella." Chapter 4 shows how the horn fifths and fanfare topics in "Per pietà, ben mio" frame Fiordiligi's choice: the Albanian or Guglielmo. Chapter 5 illustrates the relationship between fanfare topics and galant recitative schemas to articulate formal boundaries between accompanied recitatives and arias. The expectations of closure emplaced by the examples from Così fan tutte nuance a reading of "Hai già vinta la causa!" from Le nozze di Figaro. Chapter 6 discusses the role of recitative intrusions and their articulation of the Count's unrest in "Vedrò mentre io sospiro." Detailed analyses and close readings of the topics and tropes in this dissertation drawn from throughout Così fan tutte showcase Mozart's rich deployment of topics in varied musical and dramatic roles.