The musical output of Mexican composer Mario Lavista can be roughly organized into three compositional periods corresponding to different techniques and media which he explored in search of his own original voice. These periods are defined in the first chapter, which also delves into Lavista's background and influences, and are represented in an annotated chronological catalogue. Ficciones, an orchestral composition belonging to Lavista's third period, shows an A-B form. Although it is an atonal piece, it has many tonal connotations derived from a germinal cell based on a perfect fifth with an upper and a lower tritone. Throughout the piece the tritone establishes all tonal areas, substituting for the V-I progression of tonal harmony. Lavista is also an influential thinker and teacher, and an interview conducted by the author in Mexico City conveys many of the composer's views on topics such as teaching, literature, analysis and composition.