Angels are symbols by nature because they have no equivalent in reality, only in the sphere of signification. The issue is further complicated by the fact that the reality of symbols arises out of conventions. When considering symbolic representations of angels, it is necessary to refer to cultural codes in which the angels as symbols can be understood. Rautavaara's commentaries provide insights into the understanding of his angelic symbols, situating them in a broader cultural context that includes numerous interrelations to art, poetry, religion, and psychology. These signs join music and the external world, creating a correspondence between music and the other arts. The correspondences between Rautavaara's musically cast angels and their external sources can be regarded as instances of musical ekphrasis. Yet there are also internal sources: Rautavaara regularly links his musical portrayals of angels with his private symbols: his childhood dreams, memories, archetypes, and myths. His numerous commentaries on the angelic series provide a spectrum of interpretative codes by which to understand angels as an extramusical phenomenon in his music.

Although separate program notes exist for each of the instrumental compositions referring to angels, the most important commentaries can be found in three unrelated sources: the program to the choral work Die erste Elegie, the documentary film about Rautavaara entitled The Gift of Dreams, and an interview he gave to the weekly newspaper National Catholic Reporter.

Rautavaara rejects the view of angels as “[…] swan-winged blondes in nightshirts presented by classical kitsch,” saying that “the world of fantasy behind the ‘Angel Series’ has met with misunderstanding.” He tries to explain the figure of the angel through other non-musical sources, drawing on literature (Rilke's poetic cycle Duino Elegies), psychology (Jungian archetypes common to all civilizations), religion (the biblical Jacob's wrestling with the angel), and private obsessions (the terrifying creature that visited him in his childhood dreams). Although Rautavaara readily describes the many associations of his musical angels, he maintains that his music remains absolute, without programs, stories, or fixed imagery.