What is the theme of the poem "A Psalm of Life" by H. W. Longfellow?

In his poem, “A Psalm of Life,” Henry Wadsworth Longfellow argues that individuals should live active, full lives rather than passively allowing life to slip away. In the first two lines of the poem, the speaker asserts: “Tell me not, in mournful numbers, / Life is but an empty dream!” Here, the speaker counters religious theology that denigrates the value of life in anticipation of the afterlife. In contrast, Longfellow’s speaker suggests that “Life is real! Life is earnest! / And the grave is not its goal.” Thus, instead of passively waiting for the afterlife, the speaker urges individuals to act and to progress.

The speaker also differentiates between body and soul. In the second stanza, the speaker states, “Dust thou art, to dust returnest, / Was not spoken of the soul.” Here, the speaker posits the composition and decomposition of the body as it turns back into dust upon death. The soul, however, lives on and will not return to dust. Rather, the soul has the ability to progress, to move forward, and to seek activity.

In the final stanza, the speaker states:

Let us, then, be up and doing,

With a heart for any fate;

Still achieving, still pursuing,

Learn to labor and to wait.

In other words, the speaker urges individuals / readers to engage in activity.  Life allows for achievement and for pursuit, argues the speaker, and the individual can “Learn to labor and to wait.”

The ambiguity of the final line has led critics to question what the speaker is waiting for. A common interpretation is that the speaker is suggesting that individuals can lead active lives on Earth while simultaneously waiting for their eternal life spent in heaven.