If you got the following, then you understood it:
Indeed, if the phrases, "letter of the law" and "spirit of the law," were found in Scripture,
your meaning would be clear from their context.
Not being found in Scripture, there is nothing to establish and guard their meaning.
And so we find the wrong-minded use regarding them that I am addressing below.
Evidently you have not encountered this form of error,
but it occurs frequently in my neck o' the woods.
It has a simple basis and a simple solution.
Its basis is Scripturally-unauthorized phrases, and its solution is not using
Scripturally-unauthorized phrases, which have no context to establish their true meaning.
Hence, my post, following:
Actually, there is no "spirit of the law" and "letter of the law" in Scripture.
The phrase "letter of the law" is wrong-headedly used to mean the external, literal sense in Scripture, or obedience to the external, literal sense of Scripture, as being deadly (kills) or unprofitable;
while the "spirit of the law" is wrong-headedly used to mean the inner spiritual sense of Scripture, or our inner attitude, as being life giving.
However, in 2Co 3:6-9, "the letter" is simply "the law written," an external standard before which all people stand guilty and condemned to death (the letter kills).
The Spirit that gives life is the Holy Spirit of the living God (v.3), not our inner attitude, or some "spiritual" sense of the words.
It is the Holy Spirit who writes that same law (the letter) inwardly "on tablets of human hearts," in fulfillment of the promise of the New Covenant (Jer 31:31-34), and the law is now an internal standard.
And the Holy Spirit likewise gives the believer love of God's law, as well as power to keep it, neither of which he had previously possessed before the indwelling Holy Spirit.
So "the letter of the law" and "the spirit of the law" are unBiblical phrases often used in opposition to one another, or as distinct and different from one another, in a wrong-headed understanding of the law and the Spirit.