Catholic Commentary
The Pivotal Prayer for Wisdom
12So teach us to count our days, that we may gain a heart of wisdom.
Psalms 90:12 contains Moses's petition for God to teach his people to number and perceive their days with spiritual awareness, recognizing each as a divinely assigned portion. This request forms the turning point of the psalm, shifting from lamentation over human transience to active petitions for God's steadfast love and blessing grounded in the wisdom of mortality.
Wisdom is not thinking about death—it's letting the awareness of your numbered days reshape how you pray and live right now.
Catholic tradition has always read Psalm 90:12 as one of Scripture's most concentrated affirmations that wisdom — true sapientia — is inseparable from a proper, graced relationship with death and time. St. Augustine, in his Confessions (I.1), captures the spirit of this verse when he writes that our hearts are restless until they rest in God; the restlessness of unexamined, uncounted days is precisely what the psalm prays to be healed.
St. Thomas Aquinas, in the Summa Theologiae (II-II, q. 19, a. 7), identifies the "fear of the Lord" as the beginning of wisdom, and connects it directly to a right regard for our final end. Psalm 90:12's request for a "wise heart" is nothing less than the desire for this gift of the Holy Spirit — the Gift of Wisdom (donum sapientiae) — which the Catechism of the Catholic Church (§1831) numbers among the seven gifts. The Catechism further teaches that wisdom "makes us judge all things in light of God and in view of their eternal destiny" (§1831). Counting our days in the psalmist's sense is exactly this: judging time by the measure of eternity.
The Second Vatican Council's Gaudium et Spes (§18) speaks powerfully to this verse: "It is in the face of death that the riddle of human existence becomes most acute… man rightly follows the intuition of his heart when he abhors and repudiates the absolute ruin and total disappearance of his own person." The prayer of Psalm 90:12 is the liturgical form of this intuition — not despair before death, but the cry for wisdom to live well in its shadow.
The Rule of St. Benedict (chapter 4) lists "to keep death daily before one's eyes" (mortem cotidie ante oculos suspectam habere) as one of the primary instruments of good works, a direct monastic crystallization of this verse's spirituality.
In an age defined by the relentless compression of attention and the cultural denial of death — where technology promises distraction from finitude and social media performs an endless, ageless present — Psalm 90:12 is a prophetic counter-word. The Catholic who prays this verse is being invited into a concrete spiritual discipline: the Examen of St. Ignatius of Loyola, practiced daily, is one of the most practical expressions of "counting our days." Each evening review of the day asks: How did I use this unrepeatable day? Where was God? Where did I turn away?
More concretely still, the verse invites Catholics to recover the ancient practice of meditating on the Memento mori — not as a morbid fixation, but as a clarifying lens. When a decision looms — a career choice, a relationship, a financial commitment — the wise heart formed by this prayer asks: "How will this matter at the end of my days? What will I wish I had done?" This is not pessimism; it is the logic of eternity applied to the ordinary. The Funeral Liturgy's entrance antiphon ("Eternal rest grant unto them, O Lord") ritually enacts what this verse prays for: that our days, properly counted, end in God.
Commentary
Psalms 90:12 — "So teach us to count our days, that we may gain a wise heart."
The verse opens with the Hebrew connective kēn ("so" or "therefore"), making it structurally consequential: everything Moses has described about God's eternity (vv. 1–2), human transience (vv. 3–6), divine wrath against sin (vv. 7–11), and the brevity of life (v. 10) now converges in a single imperative petition: hôdaʿ — "make known," "teach," or "cause us to know." This is not passive reflection but an active request for divine instruction. Moses acknowledges that unaided human reason cannot truly reckon with mortality; only God can reveal its full weight and meaning.
The phrase "count our days" (limnôt yāmênû) is deceptively precise. The verb mānāh means to number, to assign, to reckon — the same root used when God "numbers" and assigns roles and portions. The psalmist is not asking for a calendar calculation but for an interior, spiritually calibrated awareness: that each day be perceived as a numbered, irreplaceable gift charged with eternal significance. This is wisdom accounting, not actuarial science.
The consequence clause — "that we may gain a wise heart" — renders the Hebrew lēbāb ḥokmāh, literally "a heart of wisdom." In the Hebrew anthropology of the Old Testament, the lēbāb (heart) is the seat of intellect, will, moral judgment, and spiritual perception all at once — a far richer concept than the merely emotional "heart" of modern usage. To "gain" such a heart (nābîʾ, to bring in, to present) is to arrive before God having acquired something precious from the raw material of finite life. The phrase implies an active receptivity: wisdom does not come automatically from living briefly, but from prayerfully attending to life's brevity before the face of an eternal God.
Within the architecture of Psalm 90 as a whole, this verse is the turning point. The first eleven verses are almost exclusively descriptive and confessional — an overwhelming vision of God's eternity contrasted with the dust-like fragility of human life. Beginning with verse 12, the psalm becomes a series of petitions (vv. 12–17), each building on the wisdom requested here. The wisdom of "counting days," then, is not merely one virtue among others; it is the foundational grace that makes all subsequent prayer and renewal possible. Without it, the petitions for God's steadfast love (v. 14), compassion (v. 13), and blessing (vv. 16–17) are groundless. With it, every moment of mortal life becomes a field of divine encounter.
Typologically, Moses as the attributed author (the only Psalm with this attribution, "a prayer of Moses the man of God") lends the verse enormous weight. The man who had seen God "face to face" (Ex 33:11), who had led a generation through the wilderness only to see them die short of the Promised Land, speaks this prayer from the ground of lived experience of human mortality in God's presence. His prayer becomes the prayer of every pilgrim people.