“So teach us to number our days that we may get a heart of wisdom.”

Psalm 90:12

Psalm 90 is a prayer of Moses. It is very interesting that it was he who was inspired by the Spirit to compose such a thought. David may have spent his days running from Saul and wondering when he would come to the power that God has promised. But when Moses had already run from Pharaoh, not once, but twice, with forty years in between, it would only be to spend another forty years with a generation that would drag him down in the wilderness, never to see what was promised.

About the exact words of this text, I would observe four truths: (i.) What it means to be taught this; (ii.) What it means to number our days; (iii.) What it means that this is wisdom; and (iv.) What it means to have a heart of wisdom.

What it means to be taught this.

God is the Teacher who would teach this, since He is the Audience addressed by the prayer, ‘Teach us.’ It helps to know that this is a promise contained in the covenant of grace: “It is written in the Prophets, ‘And they will all be taught by God” (Jn. 6:45). God is also the Giver of that which is taught. The heart of wisdom is shaped by the teaching of God’s word, but the heart must be given first by His Spirit (Ezk. 36:26; Jn. 3:3). Often it must be taught by having the trophies of time taken away from us. It was in Job’s suffering that he cried out,

“My days are swifter than a runner; they flee away; they see no good. They go by like skiffs of reed, like an eagle swooping on the prey” (Job 9:25-26).

God is the ultimate Teacher here, but He has teaching assistants, and the strictest among them is experience. How many people only come to number their days because they have lost loved ones, or even lost a limb or their livelihood? We see this in another of Job’s laments, “For when a few years have come I shall go the way from which I shall not return” (Job 16:22). It was by suffering loss that Job came to teach us. The truth is that the majority can only learn to rightly count in this way; and yet the Psalmist holds this out to us as a prayer that God can teach in a more merciful way. 

What it means to number our days.

This is not that we can know the literal length of our life. Only the Lord knows that. 

This is a spiritual numbering of days—that is, an awakening to the shortness of them compared to eternity and their ultimate reason for being. It is the section directly leading up to verse 12 that clearly shows what it means to number our days in this spiritual manner.

“For all our days pass away under your wrath; we bring our years to an end like a sigh. The years of our life are seventy, or even by reason of strength eighty; yet their span is but toil and trouble; they are soon gone, and we fly away. Who considers the power of your anger, and your wrath according to the fear of you?” (vv. 9-11)

Here the shortness of life and its trouble and futility are surrounded by an emphasis on God’s wrath. Why? The Psalmist here is inspired. He is filled with the Spirit. The one who would read this for profit would also be loved by God. And yet to consider this is to be mindful of divine displeasure. How do we make sense of that? Even we who believe must always remember that death is brought about by sin. While for those in Christ, the second death has no power, nevertheless the first death still meets us. The point is not to ponder so as to make fall back into condemnation, but rather to chase away any hope in this life which is wasting away. 

It will be said, “But even a pagan can have an awareness of the shortness of life. The Stoic philosopher Seneca even wrote a book about it, and many others have famously discussed it. How then is it spiritual?” The answer is suggested by Paul, where he says, “that you may not grieve as others do who have no hope” (1 These. 4:13). We do not deny that the unregenerate may also number his days. But the pagan moralist still has an anchor cast in this world and no hope beyond. He may bring up the subject so as to seem wise, but what is the moral of his story? You will notice that it is not simply to make better use of the time, but that this better use is entirely motivated by that time being all one has. Time is not a means to the end of eternity for the pagan, but is the whole of the ends. Not that the Christian is being asked to ignore action in this world. That would not be wisdom. The key is the location of one’s hope. 

What it means that this is wisdom.

Wisdom is knowledge for proper living. The wise person does not simply know things. He knows how to live. He knows how to relate his knowledge to matters of life and death. And he knows where to look for more of that wisdom. Paul says,

“Look carefully then how you walk, not as unwise but as wise, making the best use of the time, because the days are evil” (Eph. 5:15-16).

Christians who know that their days are few and ordained by God live differently than those who live under presumption or who numb themselves to this reality. It is not only that the days offer no hope in themselves, but because they are furnished with all of those distractions depicted by Bunyan’s Vanity Fair, the Bible can call such days “evil,” as they are worse than being unsuitable to cast the anchor of hope. They are made of quicksand to hell. 

In contrast to the wise in Scripture is the fool. The fool is not marked so much by not grasping these things. He sees them on paper well enough. But he turns away quickly, or he may even roll his eyes if the messenger has become a stench to him. What the fool doesn’t realize is just how bitter that day will be when he cannot have this time back. He thought time was on his side; but time has no thought of any of us. It will not care when the regret sinks in. The Proverbs are an inspired book filled with wisdom. Their sayings are things which strike us as so simple, and yet left so undone. If they are so simple, why can we not do them? 

“Slothfulness casts into a deep sleep, and an idle person will suffer hunger” (Prov. 19:15).

“and slumber will clothe them with rags” (Prov. 23:21).

The fool sees the simplicity of wisdom and despises it, as the Pharisees despised the parables as children’s stories. Who doesn’t know that a man who will not work will not eat! But no one in the flesh understands that he who will not labor in eternal time will not eat the food that never spoils. The wisdom in this comes when the conviction pierces us, and makes us begin to hate the enemies of time well-spent. 

What it means to have a heart of wisdom. 

This isn’t about stopping to smell the roses, much less making time slow down. No one can do that. Time doesn’t slow down for any of us. It also won’t wait for us to start serving Christ’s kingdom “once things get better.” What masquerades as prudence is often excuse-making. That is the sense of James’ warning to those who seek the treasures on earth. It is not only a warning against the brashest sort of business.

“Come now, you who say, ‘Today or tomorrow we will go into such and such a town and spend a year there and trade and make a profit’— yet you do not know what tomorrow will bring. What is your life? For you are a mist that appears for a little time and then vanishes. Instead you ought to say, ‘If the Lord wills, we will live and do this or that’” (Jas. 4:13-15).

A wise heart will not only be mindful of the best use of his hands in the time that remains, but also the best use of his words: It is not only that “mere talk tends only to poverty” (Prov. 14:23), which would be bad enough, but that small-talk builds only small souls, which have no room for heavenly things. There is nothing wrong with taking note of this or that in the world, but if we are using small talk to silence big truths, then our discomfort is really an uneasiness with eternity. So, “The tongue of the wise commends knowledge” (Prov. 15:2). It is not only for the preacher but for every Christian to speak as dying men to dying men.

Uses of this Doctrine

Use 1. Admonition. There is great temptation in thinking your days to be innumerable, or the length of life indefinite. It was the first lie of all and it is contained in all the others that followed. The lie is that, “You will not surely die” (Gen. 3:4).

There is a great danger in not numbering our days. The devil hardly needs to cast his net wide if the sinner already does so by his imaginary never-ending day. Modern people think that pondering death is morbid, but the saints throughout the ages have discovered that pretending it isn’t there is the surest way to get there the worse off, that is, to be unprepared.

Lucretius, that ancient skeptic, scoffed at all religion, saying that the believer wastes his life in fear; but in truth it is the man who pretends that death is inconsequential who never really lives. This is more than Pascal’s Wager talking to us. It is not simply that, “The man who is living his life as if there is no hell had better be right.” This is not a gamble on the odds between two equal opposites. If time is a vapor and eternity the incomparable reality behind its veil, then such a man had not simply “better be right,” but rather had better find out right now. What could be more hateful to one’s soul and the soul of others than to fail to discover such a reality? Nothing could be more worthy of our time than this wisdom.  

Use 2. Consolation. The wisdom about this time is that it is eternal-time. In other words, these words are not only there to exhort us to live in light of eternity, but they are to drive us to the cross so as to remember that God has redeemed the time as only He can. However much time you have behind you and however much more in front of you—however much you may have wasted—know that, in Christ, the life that never ends can infuse with grace the rest of the time that does end.

And recall the words of Paul, which point back to the resurrection of Christ and then forward to a reward for whatever we have done in time for Christ, however inconsequential it may seem to those who cannot tell the time:

“Therefore, my beloved brothers, be steadfast, immovable, always abounding in the work of the Lord, knowing that in the Lord your labor is not in vain” (1 Cor. 15:58).

It is this thought which is also captured in the maxim: Only one life. ‘twill soon be past. Only what’s done for Christ will last.