Why is Henry Wadesworth Longfellow's "A Psalm of life" considered romantic

In "A Psalm of Life" by Henry Wadsworth Longfellow, one Romantic theme that is portrayed is the exploration of the inner world of human nature. Longfellow states that it is human nature to progress and develop. He explains his beliefs when he says, "And the grave is not its goal;

dust thou are, to dust thou returnest, was not spoken of the soul". These lines from the poem show Longfellow's idea that our lives on Earth have a meaning; we don't live just to die. He believed that everyone had a role to fill in the world and a person's soul never dies. This psychological type of literature where the author's thoughts and intuitions are expressed are indicative of the writing style of the Romantics.