Short answer: Psalm 90:12 is a prayer to live wisely by remembering that life is short. To "number our days" means to face honestly that our time is limited, so that we invest it well and gain "a heart of wisdom" instead of drifting through life.
The context: Moses on human frailty
Psalm 90 carries the heading "A Prayer of Moses the man of God" — the only psalm attributed to Moses. Its theme is the vast gap between God's eternity and human mortality. Earlier verses say a thousand years are like a day to God (v. 4) and that our years pass "as a tale that is told" (v. 9, KJV). Against that backdrop, verse 12 is the turning point: given how brief life is, teach us to live wisely.
What it means, phrase by phrase
The King James Version reads: "So teach us to number our days, that we may apply our hearts unto wisdom" (Psalm 90:12).
- "So teach us" — Wisdom about time is something we must be taught by God; it does not come naturally. Left to ourselves, we assume we have more time than we do.
- "to number our days" — To count them, to reckon honestly that they are finite. Verse 10 has just said our years are around seventy, or eighty with strength. This is not morbid; it is realistic.
- "apply our hearts unto wisdom" — The goal of counting your days is not anxiety but wisdom — literally, to bring the heart to wisdom, to let the shortness of life reorder your priorities.
The logic runs backward from how we usually think. We assume wisdom leads to a good life; Moses says awareness of death's nearness is what pushes us toward wisdom in the first place.
Cross-references
Scripture returns often to life's brevity as a call to wise living:
- James 4:14 — Life "is even a vapour, that appeareth for a little time, and then vanisheth away" (KJV).
- Ephesians 5:15–16 — Walk wisely, "redeeming the time, because the days are evil" (KJV).
- Psalm 39:4 — "LORD, make me to know mine end... that I may know how frail I am" (KJV).
- Ecclesiastes 3:1 — "To every thing there is a season, and a time to every purpose under the heaven" (KJV).
How to apply Psalm 90:12 today
Numbering your days is a practice, not a mood. Ask honestly: if my time is limited, am I spending it on what matters — relationships, faith, work that lasts — or on distractions I would not choose if I remembered the clock? Many people pray this verse at a birthday, a new year, or after a loss, letting the reminder of life's length reset their priorities. The aim is not fear of death but wisdom in life.
Frequently Asked Questions
Who wrote Psalm 90? The heading attributes it to Moses, making it likely the oldest psalm in the collection. Its meditation on human frailty fits Moses' long experience of leading a generation through the wilderness.
Is "numbering our days" about being afraid of death? No. It is about honesty, not fear. Remembering that life is short is meant to produce wisdom and good priorities, not dread. The verse aims at a well-lived life.
What is "a heart of wisdom"? In Hebrew thought the heart is the center of the will and understanding, not just emotion. A heart of wisdom is a whole inner life shaped by good judgment — choosing what truly matters because time is short.