A. Kircher was the first to give a description of G. Carissimi’s spiritual dialogue Jephte and to publish a fragment of it in his treatise Musurgia universalis. He also put this work into the context of ideas of Roman musical humanism of the mid 17th century. This paper presents the first ever analyses of Carissimi’s work in the light of Kircher’s theory of musica pathetica. In particular, the tonal plan is considered in relation to the concepts of mutatio toni and stylus metabolicus, while the overall structure of the dialogue is regarded in connection with different classifications of the musical affects. In addition, an observation is made of the probable influence of ancient theatre’s models on the concept of this work. In the appendix two Russian translations are inserted: of the libretto of this spiritual dialogue (made by author of the paper) and of the text of the Carissimi’s secular dialogue I Filosofi (prepared by Marina L. Nassonova).