What does Psalm chapter 90 mean?This psalm is attributed to Moses. It seems to have been inspired by Israel's wandering in the desert, which was punishment for their disobedience at the borders of the Promised Land (Numbers 13—14). That would make this the oldest text in the collection of Psalms. It's notable that the eldest psalm would contain a reference to the brevity of human life, as seen in verse 10.
Moses opens this psalm with a clear contrast. God is eternal and everlasting; man is temporary and created. The opening phrases establish that God is beyond time and the universe; He has no origin or creation. Rather, as God stated to Moses (Exodus 3:14), He simply "is." Human beings, on the other hand, die and return to the dust from which they are made (Psalm 90:1–4).
One reason for life's brevity is human sin. Judgment from God comes on those who provoke His wrath. Moses uses the analogy of grass, which can change from green and healthy to withered and dead very quickly. As echoed in other parts of Scripture (Hebrews 4:13), God is able to see all things, including secret sins (Psalm 90:5–8).
Because of human sin (Romans 5:12), our lives end like a soft, fading puff of breath. The typical human being, on average, seems to live for about 70 to 80 years. Those with especially good circumstances might live to well over 100. Yet even those who outlive their peers will still die. For this reason, Moses wonders who—if anyone—bothers to consider what will happen when they face judgment before God. In fact, the idea of "number[ing] our days" is directly tied to a wise perspective. A key step in understanding our position before God is realizing our own mortality (Psalm 90:9–12).
Moses ends this prayer with a plea for God to rescue and enlighten His people. The cry of "how long" is a common one from the Old Testament (Psalm 6:3; 35:17; 89:46; Isaiah 6:11; Habakkuk 1:2). It's normal in the middle of hardship to wonder when, or even if, God will respond. And yet, Moses expresses faith that God will give Israel reasons to rejoice. He especially asks for God to demonstrate Himself to the people, to encourage their faith. The psalm ends with a repeated request for God to bless Israel's efforts (Psalm 90:13–17).