Letter 140: Cyprian had visited Jerome at Bethlehem and had asked him to write an exposition of Psalm XC. in simple language such as might be readily understood. With this request Jerome now complies, giving a very full account of the psalm, verse by verse, and bringing the treasures of his learning and especially his knowledge of Hebrew to bear upon it.
Jerome to the presbyter Cyprian — greetings.
You came to Bethlehem and asked me, with a simplicity that I found disarming, to write you an exposition of Psalm 90 in plain language — language that anyone could follow without needing a library. I will try to honor the request, though plain language and the ninetieth Psalm are not the most natural companions.
The Psalm is attributed to Moses. I believe this attribution is correct, though I want to be careful: Moses may have spoken these words not in his own name but on behalf of the Jewish people, as a spokesman for the nation rather than as an individual pray-er. The distinction matters for interpretation.
The Psalter as a whole falls into five books, mirroring the five books of Moses. It is a mistake — a common one — to attribute all 150 psalms to David; many have different authors, and the Psalm headings should be taken seriously as evidence of authorship, not dismissed as later additions.
Psalm 90's central theme is the brevity of human life in contrast to God's eternity. "Lord, you have been our dwelling place in all generations. Before the mountains were brought forth... from everlasting to everlasting, you are God." Against this background of divine permanence, human life appears as grass that flourishes in the morning and withers by evening. This is not pessimism; it is realism. The soul that has grasped the comparative brevity and fragility of human existence is the soul prepared to orient itself rightly.
The Pelagians would object, of course, that dwelling too much on human weakness undermines the will to moral effort. My response is that it does exactly the opposite: a man who knows he has seventy years and not a moment guaranteed beyond them is the man who understands that there is no time to waste on things that do not last.
Modern English rendering for readability. See the 19th-century translation or original Latin/Greek for scholarly use.
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