In 1971 Guðmunda Andrésdóttir held a one-woman show at the National Museum of Iceland, where she exhibited paintings she had been working on for almost five years. In the History of Icelandic Art II (p.150) these pieces are described as follows: “[They are based] on a two-part picture plane and a horizontal composition. Horizontal lines lie in parallel, criss-crossing over the picture plane: they form a kind of constant musical stave of varying width. In order to introduce movement to the circular forms, Guðmunda uses arched and curved lines which amplify the power and sense of motion.” An article from a exhibition catalogue of 2004 says: “thus the circular form, its mobility, geometrical nature and spatial effect in the picture plane becomes the fundamental theme of her explorations for the subsequent three decades.” (Hanna Guðlaug Guðmundsdóttir: Guðmunda Andrésdóttir: Tilbrigði við stef (Guðmunda Andrésdóttir: Variations on a Theme), p. 47–50). This piece, Autumn Sun, is a painting of this kind, and some other pieces owned in the Reykjavik Art Museum collection also give a hint of this formal approach.
In the aforementioned catalogue Guðmunda's symbolism is compared to that of Modernist artists such as Delaunay and Kupka's experiments with transporting music to the picture plane: “Kupka ‘transposes’… time and movement onto the picture plane, as would a composer if this were a musical piece.” In Delaunay's work colours became “tones, colour expression appears in a fugal form, circular and spiral forms, which enlivened the immobile canvas with dynamic forms and rhythm. … The musical reference is obvious … Guðmunda's use of colour, however, often appears to be a function of the movement in the piece, intended to enhance or decrease it, rather than being grounded in colour theory, inner reality and the relationships between colours ...” (Hanna Guðlaug Guðmundsdóttir: ibid.)