Moses affirms in this psalm that God is an everlasting reality, existing before He created the earth. But having established God's eternal nature, Moses cries out that this same God quickly turns us humans back to dust. Though we might live eighty years, we are insignificant to God who sees a thousand years as though they were yesterday, fading like a sigh. Moreover, during our moment of life, we live consumed and overwhelmed by toil and trouble and by God's anger because of our iniquities.
Moses asks how this wrathful eternal being can provide comfort to us humans whose life passes "like a watch in the night," then "we fly away"? Perhaps, Moses thinks, if God will teach us to pay close attention to the passing of our days "we may gain a wise heart."
But as though suddenly realizing that wisdom is not enough, he cries out for God to change, to transform his anger into compassion! Driven by pain, Moses prays for God to become a compassionate God instead of a judgmental God of wrath.
Moses asks God to satisfy us humans with "steadfast love," enabling us to "rejoice and be glad all our days." Then, maybe realizing that he has asked too much, Moses envisions a life when we are made glad "at least as many days as you have afflicted us."
In this new vision, humans can hope that God's favor will be revealed more than His wrath. A compassionate God might enable the "work of our hands" in this brief life to prosper, to give some meaning to this life which God sweeps away like a dream, which fades and withers before flying away.
This is an Advent poem, a song that God might one day use His "glorious power" to provide some glad days and meaningful work for our hands. For Christians, the psalm suggests that Moses' longing for a compassionate God would be satisfied in what we now call the Christmas story.