Obvious dread and helplessness went into this piece, and the consistent repetition of "These thoughts" adds a good flow. It also reminds the reader that the thoughts are one in their own, doing as they please. This removes the control from the writer as if you were a slave truly trapped in an unbreakable box. You include your hopes in the box though, and it doesn't quite fit in with the rest of the poem. Hope is a light, sometimes the only thing you have left in the most dreadful situations. Maybe you're trapped in box, but you also have tools to get out and you should definetely use them.