C major, in binary form.

A [a (measures 1-4) + a1 (measures 5-8)]

B [b (measures 9-12) + concluding b1 (measures 13-16)]

The theme spans measures 1-4. What is interesting is its commencement with a subdominant IV as an imperfect cadence. While in the Classical period, the dominant was typically the starting chord for an imperfect cadence, in the Romantic period, the subdominant also began to be used as the starting chord for imperfect cadences.

 On the other hand, this opening suggests a Lydian mode with F as the final, rather than C major. Given the title "Hymn," it is possible that this piece was intentionally composed to evoke a partial sense of church modes.

 Section b develops using the rhythm of the theme. While the harmony descends chromatically, measures 9-10 partially modulate to G major, moving from I to V, creating harmonic tension. In contrast, measures 11-12 resolve the harmony through a secondary dominant IV6 to I chord. Thus, within the same chromatic progression, there are two different harmonic relationships. One should consider how to express these subtle changes.