Wordsworth was one of the leading figures of English Romanticism,  Romanticism drew on feelings, often provoked by the solitary contemplation of nature. Wordsworth, for instance, described poetry as the “spontaneous overflow of powerful feelings” “recollected in tranquility”; in other words, poetry is a calm recollection of intense emotion.

“The Solitary Reaper” is a clear example of Wordsworthian Romanticism, since its speaker reflects on a powerful experience of nature from a tranquil distance.

The poem presents two sets of actions. 
On the one hand, the reaper “cuts and binds the grain / and sings a melancholy strain.” On the other hand, the speaker and the reader “Behold” and “listen.” There is thus an implicit distinction between the reaper and the speaker in terms of their relationships with nature

The reaper is implied to be closer to a “natural” existence than the speaker. In the terms of Romantic thought, she is also therefore implied to be closer to the source of poetry itself, since poetry comes from nature. 

As the speaker admires the reaper’s proximity to nature, however, he reduces her participation in human history and politics. He treats the reaper as something to observe, to draw inspiration from, and something ultimately separate from his world and its concerns.