The famous evangelist, Billy Graham, was asked what most surprised him in life. He answered, ″Its brevity." Psalm 90 is a brutally honest psalm in which Moses reflects on God's eternity and, in the light of that, our mortality.

Psalm 90 begins Book 4 of Psalms. It is the only psalm written by the great lawgiver, Moses. The title is, ″The prayer of Moses the man of God.″ It's a poem or prayer in three parts.

Verses 1-6 lay the necessary foundation for what is to follow. God is unceasingly faithful to His people. Moses stands in awe at the fact of God's eternal existence. But this isn't just a comforting reminder to him, it's also a sobering reminder of humanity's brief life. If God is forever, we pass in the blink of an eye. This puts our contemporary boastings about a long life into perspective. We boast that we might live for 100 years, but this is barely ″a watch in the night″ against God's eternity (v. 4).

In verses 7-12, Moses isn't satisfied to simply reflect on the shortness of our days. He confronts us with the equally unpleasant fact of what these days are like. They are full of sorrow and turmoil (vv. 9-10). His words take us back to Genesis 3 and God's judgment on men and women because of sin. God had said, ″Cursed is the ground because of you; through painful toil you will eat food from it all the days of your life″ (Genesis 3:17). Humanity's work would be hard and frustrating. And glorious childbirth would come in terrible agony (v. 16). Why is life like this? Moses reminds us that it's because of sin and God's anger (Psalm 90:7-9).

So, stop, says Moses. Sit down and take a good hard look at life. Pull out your calculator and do your sums. Learn wisdom from the brevity and bleakness of life (v. 12).

Since sin is the root cause of our troubles, the solution is divine compassion (v. 13). Moses' prayer doesn't end with despair (vv. 13-17). He prays for his people to know God's unfailing love so they can ″be glad all our days″ (v. 14).

Moses never lived to see the answer to his prayer. He couldn't foresee a day when our brief lives would turn into eternal life, and our sorrow transformed into joy. While Moses longed for the day when he could ″sing for joy″ (v. 14), every Christmas Christians sing, ″Joy to the world the Lord has come″. What Moses could only pray, we see and experience in the cross of Christ. It was there that our sins, both open and secret (v. 8) were washed away. On the cross, Jesus was consumed by God's anger (v. 7) so that the favour of the Lord might rest on us (v. 17).