Read the following poem, then answer the question. Barnacles

My soul is sailing through the sea,
But the Past is heavy and hindereth me.
The Past hath crusted cumbrous shells
That hold the flesh of cold sea-mells
About my soul.
The huge waves wash, the high waves roll,
Each barnacle clingeth and worketh dole
And hindereth me from sailing!

Old Past, let go, and drop i' the sea
Till fathomless waters cover thee!
For I am living, but thou art dead;
Thou drawest back, I strive ahead
The Day to find.
Thy shells unbind! Night comes behind;
I needs must hurry with the wind
And trim me best for sailing.
—Sydney Lanier

What is the central idea of this poem? Provide support for your answer from the text. Your answer should be 2-3 sentences.