By St. Augustine of Hippo
The Fear of God is Man's True Wisdom
The true wisdom of man is piety. You find this in the book of holy Job. For we read there what wisdom itself has said to man: "Behold, the fear of the Lord [pietas], that is wisdom." If you ask further what is meant in that place by pietas, the Greek calls it more definitely θεοσέβεια, that is, the worship of God. The Greeks sometimes call piety εὐσέβεια, which signifies right worship, though this, of course, refers specially to the worship of God. But when we are defining in what man's true wisdom consists, the most convenient word to use is that which distinctly expresses the fear of God. And can you, who are anxious that I should treat of great matters in few words, wish for a briefer form of expression? Or perhaps you are anxious that this expression should itself be briefly explained, and that I should unfold in a short discourse the proper mode of worshipping God?
God is to Be Worshipped Through Faith, Hope, and Love
Now if I should answer, that God is to be worshipped with faith, hope, and love, you will at once say that this answer is too brief, and will ask me briefly to unfold the objects of each of these three graces, viz., what we are to believe, what we are to hope for, and what we are to love. And when I have done this, you will have an answer to all the questions you asked in your letter. If you have kept a copy of your letter, you can easily turn it up and read it over again: if you have not, you will have no difficulty in recalling it when I refresh your memory.
Read the rest at this link: The Handbook on Faith, Hope and Love