Answer:
The main idea of this poem is that it is wise to forget about the bad memories in the past and move forward by doing good things. The poet's "soul is sailing through the sea,/But the Past is heavy and hindereth" him. If anyone considers the past as a burden- "Past is heavy", then it will trouble (as is found in the poem, "hindereth") and not let anyone do the works and achieve their dreams.
At first, his soul is sailing, which means that he is happy and relaxed but soon his past starts destroying his mood; he feels sad. However, the speaker, like Robert Frost's "Stopping by Woods on a Snowy Evening", becomes positive and determined: "Old Past, let go, and drop i' the sea,/Till fathomless waters cover thee!" He wants to forget his past; he wants to think about the present moment, "I strive ahead" and the accomplishment in the future "The Day to find". He wants to find the "Day"; he has a goal in life; he wants to achieve his dream.
The barnacle attaches itself firmly and to rocks and the undersides of boats but the poet does not want to stick to one place like the barnacle. He wants to move; he wants to "strive ahead". Barnacle can also be compared to the 'past'. Barnacle sticks to rocks, similarly the poet's past sticks to his soul and he wants to be free from it. The poem slowly reaches a conclusion with the note of optimism as he says that the past is dead and he is alive, "For I am living but thou art dead." His soul is ecstatic again as he utters, "I needs must hurry with the wind/And trim me best for sailing."
Step-by-step explanation: