"Fear God and keep his commandments, for this is the duty of all mankind." (Ecclesiastes 12:13)
Remember your Creator in the days of your youth, before the evil days come and the years approach when you will say: I find no pleasure in them - before the sun and the light and the moon and the stars grow dark, and the clouds return after the rain. When the doors to the street are closed and the sound of grinding fades; when people rise up at the sound of birds, but all their songs grow faint; when people are afraid of heights and of dangers in the streets; when the almond tree blossoms and the grasshopper drags itself along and desire no longer is stirred - then the dust returns to the ground it came from, and the spirit returns to God who gave it. The Teacher's closing conclusion, after testing everything under the sun: fear God and keep his commandments, for this is the duty of all mankind. For God will bring every deed into judgment, including every hidden thing, whether it is good or evil.
The Catechism identifies the fear of God and the keeping of his commandments as the whole duty of the human person: the conclusion of the Teacher is the same as the beginning of Proverbs and the foundation of all wisdom (CCC 2112).
Brothers and sisters, the Teacher has tested everything and returned to the beginning: fear God and keep his commandments. This is not a retreat from wisdom but the destination of it. After every experiment, every observation, every honest assessment of what human achievement produces, the Teacher arrives where every wise person eventually arrives - at the beginning of wisdom. Fear God. Keep his commandments. This is your whole duty. Do it.
Lord God, we fear you and keep your commandments. This is our whole duty. Judge every deed, including the hidden ones, with mercy and justice. Through Christ our Lord. Amen.