Sonata Etere is characterized by bimodal/bitonal effects, fixed, continually varied rhythmic patterns, and shifts of accent. The work takes approximately 30 minutes to perform.
The sonata makes do with only two main themes, designated In Cerca Di (In search of, henceforth referred to as the first theme) and Tono Etereo (ethereal tune, henceforth referred to as the second theme) Both the themes of the work are introduced in the first movement.
The developmental nature of this exposition is similar to traditional sonata procedure. There is a marked difference, however, in that the themes themselves retain their original form, rather than being chopped up into pieces as they would be in, say, a sonata by Beethoven. As developmental tools go, more emphasis is placed on alternating rhythmic patterns and shifts of key and accent.
In measure 212 we reach a recapitulation. This section of the piece is an altered repeat of the beginning of the exposition. It retains many of the basic elements of the exposition but many facets, such as key, are changed. The recapitulation is broken off in measure 263, and leads to a coda: the first theme builds to a sonorous climax, and strains of the second theme close the movement.
Most of the sections are variations on the second theme, but the movement breaks with traditional variations procedure by section 15 - from that point on the first theme is brought back in and the two themes undergo a common development which might remind one of the first movement.