Many commentators remark on the amount of repetition within the first movement of Beethoven’s Symphony No.6. Antony Hopkins, in his book The Nine Symphonies of Beethoven, sees it as another metaphor for nature:

One of the most notable characteristics of the entire first movement is its exploitation of repetition, the repetition of pattern that we find throughout nature. We do not need to count the leaves of an oak tree to be aware of their similarity, nor, when we see a meadow brightly comparisoned with buttercups and daisies, do we mistake one for the other. Beethoven is concerned to capture both the infinite similarity and the infinite variety of nature’s patterns; therefore he gives us an unusual amount of repetition but also many subtle deviations.
Antony Hopkins, The Nine Symphonies of Beethoven

Hopkins goes on to explain that many of Beethoven’s pieces use repitition as a device, but the effect within the 6th symphony is quite different from anything else he wrote:

The markedly different effects can be attributed to the very slow rate of harmonic change. For instance, starting from bar 151 we find twelve bars of Bb major followed by no less than twenty-four bars of D major. The unusual element in this symphony is not therefore repetition of one rhythmic figure, a device which may be found in numerous movements by Beethoven, but the combination of compact repeated patterns with long sustained harmony…

In his Charles Eliot Norton lecutre on Musical Semantics at Harvard in 1973, Leonard Bernstein analyses the 6th Symphony. He is concerned with viewing the symphony from a purely musical standpoint, rather than an extra-musical (ie programmatic) one:

It could be suggested that this compulsive repeating on Beethoven’s part is related to the programmatic meaning. After all it’s a nature piece and the profuse repetition could be a metaphor for the profuse repetitiveness of nature herself, the infinite reduplication of species, of jonquils and daisies, and sparrows and poplars and mosquitos, to say nothing of the regular movements of sun, stars and moon. But this is not the kind of metaphor we’re seeking, because it’s extrinsic and extra-musical. What is the musical metaphor? In a nutshell, it’s to be found in the large design that is formed out of these bar-by-bar repeats.

Bernstein focuses on the musical figure repeated relentlessly in the first movement, specifically its appearance at bar 151:

There are two different orders of articulation, two different sub-structures fuctioning simultaneously within this single span of 24 bars. One order articulates the orchestral texture, and the other one articulates what Walter Piston calls the ‘harmonic rhythm’. The simultaneous contradiction of the two creates one glorious ambiguity – ‘this is that’, or better, ‘this but that’. And thus is born a great musical metaphor.