We often think of wise people as calm, cool, and collected, but in "Do Not Go Gentle into That Good Night," wisdom means a determination to struggle. Even if the struggle isn't pretty, even if it means ranting, raving, crying, screaming, and pounding your fists on the floor, the speaker believes that is more dignified than simply lying down and giving in to fate.
The knowledge of life's brevity makes the speaker of "Do Not Go Gentle into That Good Night" feel a tragic sense of loss, even as he's beholding the beautiful aspects of the world.