The eolian harp, the instrument produces music when the wind blows across its strings, becomes part of the poem's conceit. Initially, in lines 14-15, the speaker refers simply to the physical harp sitting in the window of the cottage. But the harp goes on to become an elaborate extended metaphor, first for the process of poetic inspiration, and then for the entirety of the living world.
In lines 41-45, the speaker compares the wild and unpredictable thoughts that come into his head to the wild and unpredictable winds that make music on the lute. Within this comparison, the speaker himself is like the lute: just as the lute takes in the motion of the wind and turns it into music, the speaker takes in the thoughts with which nature inspires him and turns them into poetry.
One thought that seems to inspire him, which he then turns into a part of this very poem, is the idea that all living things (not just poets) could be considered "organic" eolian harps. This idea leads to the most fanciful version of the harp conceit yet, as the speaker imagines that, just as the eolian harp is brought to life musically by a physical breeze, all of nature might be "animated" by an "intellectual breeze."
The fact that Coleridge conveys this idea of nature through a poetic conceit is significant. His image of all living things being brought to life, essentially, by a single breeze breaks down barriers between human beings and the natural world they inhabit, emphasizing that people and the rest of nature share a single source of life. This reflects the literary device actually being used in the poem: a poetic conceit works similarly to break down barriers by comparing things that might initially seem very different. A harp is a man-made instrument not found in nature. By saying that living beings are like "organic Harps," or “natural” harps, the speaker breaks down the barrier between the human world and the natural world. The conceit reinforces the sense of how closely those two worlds are connected.