Is the psalm of life a negative or positive poem?

"Lives of great men all remind us

We can make our lives sublime,

And, departing, leave behind us

Footprints on the sands of time;--"

The above extract from Longfellow's poem, "A Psalm of Life" can leave us in no doubt as to the positive message of the poem. It is from start to finish a very positive poem, which though it does not deny that there is an end to life on earth, we can, each and every one of us, by the way we live our lives make the world a better place.