This presentation demonstrates the significance both historically and aesthetically of the obscure Portuguese composer Carlos Seixas, (1704-1742), to the development of the keyboard sonata during the transitional period between the Baroque and Classic eras. The relationship between Seixas and his better-known colleague Domenico Scarlatti is explored and particular musical styles and techniques generally assumed as innovations of the latter composer are shown to exist in keyboard works of Seixas which probably pre-date those of Scarlatti. Thematically-related multi-movement sonatas and structural techniques anticipating the ternary single-movement sonata design are illustrated in several of Seixas1 sonatas. In addition to the recorded performance of selected sonatas by Seixas, this dissertation includes three tape recordings of selected piano works by J. S. Bach, Barber, Beethoven, Chopin, Franck, Prokofieff, and Scriabin.

(Jose Antonio) Carlos de Seixas (1704-1742) is an important figure in the European keyboard music of the beginning of the 18th-century. He composed around 700 sonatas for keyboard, of which only around 105 are known today. They demonstrate a high execution level that can be compared with J. P. Rameau (1683-1764), J. S. Bach (1685-1750), Domenico Scarlatti (1685-1757), Padre Antonio Soler (1729-1783) and other important composers of his time. Like Scarlatti and Soler, Carlos Seixas is positioned in an important transitional period in the history of music. He and his contemporaries are situated between true giants of Western Art Music: before and, in part, during Seixas's life time lived G. F. Haendel (1685-1759) and J. S. Bach (1685-1750); and after Seixas came F. J. Haydn (1732-1809), W. A. Mozart (1756-1791), and L. van Beethoven (1770-1827). During this transitional time in the first half of the eighteenth century, from the baroque to the classical eras, several stylistic trends coexisted--- the baroque, the new galant style, the empfindsamer Stil, and the pre-classical. This essay is divided into four chapters. In Chapter One I discuss the sources for Seixas scholarship followed by a historical overview of seventeenth- and eighteenth- century Portugal as well as a brief biographical sketch of Seixas's life. Chapter Two includes a discussion of Seixas's musical style and form. I examine various facets of his compositional style, including some commonalities found in many composers' works during the transitional period between the Baroque and pre-Classical. I also explore other facets of his keyboard writing such as the use of violin idioms, folkloric sounds, and symphonic textures. In Chapter Three I examine in greater detail Seixas's keyboard writing. I start with descriptions of the instruments that Seixas may have used and of his keyboard writing. I also examine available scholarship for guidelines on performing early eighteenth-century keyboard music in general--including specific approaches to ornaments, articulation, improvisation, rubato, and the like--before turning to Seixas's keyboard sonatas in particular. The last chapter, Chapter Four, includes elements for the analysis of Seixas's sonatas; I choose four of these sonatas for more in-depth analysis of formal and tonal structure. The four selected sonatas represent different formal schemes and stylistic characteristics, which demonstrate the variety within Seixas's solo keyboard pieces. They show great contrasts in form, relationship of movements, and thematic treatment: Sonata No. 16 in C minor presents only one movement in free binary form; Sonata No. 27 in D minor has three movements with no evident relationship among them and toccata elements in the first movement; Sonata No. 42 in F minor also has three movements but the last two movements relate thematically and the first movement presents imitative counterpoint; and Sonata No. 59 in A major represents pre-classical tendencies in texture and structure, presenting three movements connected as a whole through cyclical thematic ideas in the outer movements and a second movement, in A minor, that links to the last movement by means of an open ending. In addition, Chapter Four includes pedagogical insights from an analytical standpoint and annotations for the use of Seixas's sonatas as teaching resources. As part of this chapter's pedagogical resources, I also list additional sources for understanding performance practice of eighteenth-century music, review the available editions of Seixas's solo keyboard compositions, and list the primary performers of his keyboard works. Finally, the appendices to this essay include two cataloguing tables: the first (Appendix A) catalogues a selected group of Seixas's sonatas with detailed descriptions of their technical difficulties, and the second (Appendix B) catalogues all eighty sonatas according to level of difficulty. In addition, the scores of all four sonatas analyzed in Chapter Four are provided in two forms: Appendices C, D, E, and F contain the original Seixas score as edited by Seixas's preeminent scholar Santiago Macario Kastner; Appendices G, H, I, and J contain my performer's scores for the same four sonatas, that is, annotated versions of Kastner's editions.