We all are forced by the stern reality of death to consider eternity seriously. When a loved one dies or a young person is taken away quickly by a tragic accident, we often ponder the end of life as we know it. Sometimes, we wonder why God spares us and takes others. Nurses and doctors, emergency workers, morticians, and soldiers in times of war often deal with death on a regular basis. If death teaches us anything, it should teach us to “number our days, that we may apply our hearts unto wisdom” (Psalm 90:12).

Psalm 90 is subtitled “A Prayer of Moses the man of God.” This subtitle is part of the inspired Hebrew text of the psalm. The subtitle reveals to us that Moses was the author of Psalm 90, and that he wrote it as a prayer. The psalmist extols the eternal nature of God and contrasts God’s eternality with the temporal and transitory nature of human life.

“Lord, thou hast been our dwelling place in all generations. Before the mountains were brought forth, or ever thou hadst formed the earth and the world, even from everlasting to everlasting, thou art God” (Psalm 90:1–2). Moses recognized that God’s eternality is unique. The angels are not eternal. The hills are not eternal. The world is not eternal. Only our Lord is truly eternal in the sense that He has no beginning and no ending. He is, as Moses asserted in verse 2, “from everlasting to everlasting.”

In contrast, man’s mortal life is headed inevitably for death and destruction. “Thou turnest man to destruction” (Psalm 90:3). The Hebrew word here translated “destruction” is the same word that is used to describe the act of crushing to powder. Charles Spurgeon said of this verse, “The frailty of man is thus forcibly set forth; God creates him out of the dust, and back to dust he goes at the word of his Creator. God resolves and man dissolves.”

In addition to powdery dust, in this psalm man’s life is also compared to grass which grows on the hillsides. Spurgeon’s comment on this verse is a memorable one: “Here is the history of the grass—sown, grown, mown, blown.” However, no matter how green and beautiful a grassy hillside may look in the freshness of a spring rain, that green grass is destined within a few short weeks to wither and die. The same is also true for man.

Moses had lived a long time and understood the transitory nature of human life. He had seen the glories and splendors of Egypt. He had seen the pyramids, among the oldest and greatest of human achievements. But these monuments to the pharaohs are also an enduring reminder that the life and achievements of man, however grand, are only temporary. New pharaohs sometimes chiseled out the names of previous pharaohs and substituted their own names. Moses knew that pyramids are only enormous graves in which the bones of dead men are preserved.

Also, Moses had lived to see several generations of Israelites come and go. He had seen the nation of Israel wander for forty years in the wilderness until the awful judgment of the Lord upon unbelief was fulfilled. “But as for you, your carcases, they shall fall in this wilderness. And your children shall wander in the wilderness forty years, and bear your whoredoms, until your carcases be wasted in the wilderness” (Numbers 14:32–33).

The fearful truth about the march of time and the approach of death is that it brings man closer and closer to the Day of Judgment. The prophet Amos warned the nation of Israel, “Prepare to meet thy God” (Amos 4:12). Likewise, Moses wrote in Psalm 90: “For we are consumed by thine anger, and by thy wrath are we troubled. Thou hast set our iniquities before thee, our secret sins in the light of thy countenance” (verses 7–8). Very distinctly, Moses knew that it was because of his sin in disobeying God in the act of striking the rock that he would not set foot into the Promised Land. Even Moses, the man of God, faced death because of the curse of sin.

If indeed this psalm was written near the end of his life, then Moses would have recently seen his brother, Aaron, and his sister, Miriam, also sink into their graves, leaving him to be the oldest man in Israel yet alive. Moses observed: “The days of our years are threescore years and ten; and if by reason of strength they be fourscore years, yet is their strength labour and sorrow; for it is soon cut off, and we fly away” (Psalm 90:10). This particular Scripture shows that the normal allotment of man’s life is seventy years. Moses himself lived fifty years beyond that time—to the age of 120. But even so, man’s strength is only, as Moses recorded, “labour and sorrow, for it is soon cut off, and we fly away.”

Solomon, the wisest man that ever lived, also wrote in a similar way about the vanity of long life. Of man’s dying, Solomon wrote, “man goeth to his long home” (Ecclesiastes 12:5). He commented about death, “Then shall the dust return to the earth as it was: and the spirit shall return unto God who gave it. Vanity of vanities, saith the preacher, all is vanity” (Ecclesiastes 12:7–8).

In the face of approaching death, Moses gave a stark warning in his prayer: “Who knoweth the power of thine anger? even according to thy fear, so is thy wrath” (Psalm 90:11). Moses had lived to see the terrifying displays of God’s power on Mount Sinai. The writer of Hebrews described the scene and Moses’ response: “For ye are not come unto the mount that might be touched, and that burned with fire, nor unto blackness, and darkness, and tempest, And the sound of a trumpet, and the voice of words; which voice they that heard intreated that the word should not be spoken to them any more: (For they could not endure that which was commanded, And if so much as a beast touch the mountain, it shall be stoned, or thrust through with a dart: And so terrible was the sight, that Moses said, I exceedingly fear and quake:)” (Hebrews 12:18–21). The writer of Hebrews reminds us that, even in the New Covenant, “It is a fearful thing to fall into the hands of the living God” (Hebrews 10:31).

At this point in the psalm, while reflecting on the coming Judgment Day, Moses prayed, “So teach us to number our days, that we may apply our hearts unto wisdom” (Psalm 90:12). We must be taught to “number our days” because considering our length of life does not come naturally. We tend to live unmindful of eternity, thinking only of the present and forgetting that before us lies a day when “we must all appear before the Judgment Seat of Christ” (II Corinthians 5:10).

As Christians, we should use every marking of the passage of time to remind us to “number our days.” How many times have you ever turned the calendar page to a new month? And regarding that “we may apply our hearts unto wisdom,” are you mindful to pause and consider what you accomplished in the month gone by? That time, that month, those days are gone and never can be reclaimed. Every idle word, every conversation wasted in gossip, every day wasted in the pursuit of vanity—these are precious moments that are gone forever!

As parents, do you teach your children to reflect on time and eternity in their birthday celebrations? Birthdays are not celebrated merely for cake, candles, and gifts. They are important days for remembrance and anticipation. Teach your children the value of time. As you light the candles on a cake, remind them of all that they have learned to do in the previous year. Perhaps they have learned to ride a bike, to read, or even to drive a car! Encourage them to grow like the Lord Jesus “in wisdom and stature, and in favour with God and man” (Luke 2:52). In these ways, you can encourage your children to “number their days” and to learn to apply their “hearts unto wisdom.”

Moses closed his prayer in Psalm 90 by asking God that His mercy and glory would rest upon the next generation of Israelites about to enter the Promised Land. All of us will one day “climb Mount Pisgah” (see Deuteronomy 34:1–5) and “fly away” (see Psalm 90:10) to stand before our Creator. We ought also pray with Moses a prayer of hope for the next generation. “Let thy work appear unto thy servants, and thy glory unto their children. And let the beauty of the LORD our God be upon us: and establish thou the work of our hands upon us; yea, the work of our hands establish thou it” (Psalm 90:16–17).