Dust thou art, to dust returnest, / Was not spoken of the soul.
The young man quotes one of the most famous lines from the Bible in order to make his point. His audience—the psalmist (and the 19th century reader)—would recognize this warning that life is ephemeral and the body returns to the ground. It is likely the psalmist said something like this, or even used this line to make his own point. The young man does not dispute that the body does indeed return to the ground, but his crucial point is that the soul does not. The soul is eternal; the soul, which is actually the true part of us, has more to do than just wait for death. By giving a different meaning to a line that the psalmist might himself have used, the young man makes his point effectively.
Learn to labor and to wait.
After a dynamic, energetic poem that advocates action and achievement, it is a little strange to end with the word "wait." It makes sense, though, when considering it within the context of American Protestantism. The Puritan tradition stressed patience and a reliance upon God, and did not believe laboring for labor's sake was useful. Waiting could actually be an action and certainly was not easy.
Act,— act in the living Present!
This is the crux of the young man's argument about the meaning of life and how to achieve it. He favors eschewing passivity and apathy for action, for dynamism, for hope. He sees the beauty and the import in exercising the body and the mind rather than sitting around and waiting for death. A man must work on himself and shape himself; he must, as critic Jill Anderson writes, "urging...the heart and the mind[,] be directed toward a number of goals—mature adulthood, moral integrity, economic success, salvation itself."
And, departing, leave behind us / Footprints on the sands of time;
This is an evocative, almost melancholy image. The men who have come before have left a path that allows us to see how they lived, and to model ourselves on their accomplishments. We should endeavor to do this as well so that someone can look at the way we lived, and take courage and receive guidance if they are suffering. However, it implies that only after one is gone can one be seen as an inspiration, which makes it harder to find encouragement in this model on a day-to-day basis.
What The Heart Of The Young Man Said To The Psalmist
This is the first part of the poem, almost a preface of sorts. It establishes who is speaking, which is useful, but also provides clues as to the overall message of the poem. First, by saying that it is the "heart" of the young man speaking, we see that it is going to be an emotional, personal response. It is not necessarily a cerebral, rational one; however, that does not negate the speech's impact. Second, referring to the man as a "psalmist" rather than a teacher or minister or scholar conjures up the discredited art of palmistry; this is done in order to suggest that the psalmist's bleak assessment of the young man's "empty dreams" is just as flawed as looking at the lines in one's hands to determine their future.