The central idea of this poem is that you past will haunt you if you make it a burden. for example, at first, the author talked about how the past "hindereth's" them: My soul is sailing through the sea, But the Past is heavy and hindereth me." Then after that, the author lets go of his past making a hindered to them no more: "Old Past, let go, and drop i' the sea, Till fathomless waters cover thee!"
sorry if all the grammars not correct i am a bit of a dummy when it comes to spelling.
:)