Which literary device is used to highlight the power of a skylark's song in these lines from a poem?

Like a poet hidden
In the light of thought;
Singing hymns unbidden,
Till the world is wrought
To sympathy with hopes and fears it heeded not.
(from "Ode to a Skylark" by Percy Bysshe Shelly)
allusion
analogy
oxymoron
foreshadowing

Question

Which literary device is used to highlight the power of a skylark's song in these lines from a poem? 

Like a poet hidden
In the light of thought;
Singing hymns unbidden,
Till the world is wrought
To sympathy with hopes and fears it heeded not.
(from "Ode to a Skylark" by Percy Bysshe Shelly)
allusion
analogy
oxymoron
foreshadowing

kyanthedoodle · Answer

So basically this line just suggests that a poet is thinking and singing.

kyanthedoodle · Answer

An allusion is very subtle and hard to define.

kyanthedoodle · Answer

An analogy is a comparison between one thing and another.

anonymous · Answer

so you think its analogy? @KyanTheDoodle

kyanthedoodle · Answer

Not exactly. It might be an analogy, but it could also be an allusion. All I know is that it's not an oxymoron or foreshadow.