Read "Escape" by Emily Dickinson. Then, answer the question that follows.

I never hear the word “Escape”
Without a quicker blood,
A sudden expectation –
A flying attitude!

I never hear of prisons broad
By soldiers battered down,
But I tug childish at my bars
Only to fail again!

Dickinson, Emily. "Escape." Poems by Emily Dickinson: Second Series, edited by Mabel Loomis Todd and T.W. Higginson. Roberts Brothers, 1891.

What is the tone in the first four lines?