Question

what do you mean by 'a fearful trill of things unknown ​

Answer 1

Answer:

Further, the fear within the trill can represent the "things unknown," the uncertainty that will accompany true freedom. While welcomed, freedom is foreign and unfamiliar to the bird, which makes it scary. If freedom is gained, the bird may be simply exchanging one type of fear for another.

Explanation:

Answer 2

Answer:

fear within the trill can tell things unknown