90:1-6 Moses began by attributing eternality to Yahweh. All generations of believers have found Him to be a protective shelter from the storms of life. God existed before He created anything, even the "world"(Heb. tebel, lit. the productive earth). This Hebrew word is a poetic synonym for "earth."
God outlasts man. He creates him and then sees him return to "dust"(Heb. dakka, lit. pulverized material). From God's eternal perspective 1, 000 years are as a day is to us (2 Pet. 3:8). This does not mean that God is outside time. Time simply does not bind or limit Him as it does us. Time is the instrument we use to mark the progression and relationship of events. God's personal time line has no ends whereas ours stretches only about 70 years.
Human life is therefore quite brief compared to God's eternality. A watch in the night was about four hours long. The years of our lives sweep past as something a flood might carry off before we can retrieve them. Our lifetime is similar to one day from God's perspective or as a flower that only blooms for one day. Life is not only brief but frail.
90:7-12 Humans only live a short time because God judges the sin in their lives (cf. Rom. 6:23). God knows even our secret sins. They do not escape Him, and He judges us with physical death for our sins.
Assuming Moses did write this psalm it is interesting that he said the normal human life span was 70 years. He lived to be 120 and Joshua died at 110. Their long lives testify to God's faithfulness in providing long lives to the godly as He promised under the Mosaic Covenant.
Since our lives are comparatively short we should number our days (v. 12). Moses meant we should realize how few they are and use our time wisely (cf. Eccles. 12:2-7). Notice how often Moses mentioned "our days"or the equivalent in this psalm (vv. 4, 5, 6, 9, 10, 12, 14, 15).
