By means of this song David attempts to lead the people to a greater awareness of God and to a greater awareness of the kind of response they should have to Him, considering Who and What He is. He begins by singing about God's revelation as seen in Creation. He says, "The heavens declare the glory of God; and the firmament shows His handiwork." The "voice" of this revelation, he says, "has gone out through all the earth, and their words to the end of the world." In short, there is no place in this world where the handiwork of God is not manifest, where the creation does not, as it were, shout forth the creating power and wisdom of it's Creator and Ruler. Even the sun's daily journey from one end of the heaven to the other clearly and powerfully declares His power and wisdom.
But while all of nature declares God's glory, that glory is even more plain in His written revelation, the Bible. In David's day, that written revelation was limited to the Torah, the first five books of the Law. But in David's mind, if he could have been acquainted with the rest of the Bible, "the Law" would certainly have included all of it. For us then, the entire Bible, Old and New Testaments alike, is in view when David sings, "The law of the Lord is perfect, converting the soul ("converting" = setting it back on track each and every time it strays). The testimony of the Lord is sure, making wise the simple . . ."
That revelation is precious because it discloses our God to us! So, speaking of its words, David sings, "More to be desired are they than gold, yea, than much fine gold; sweeter are they than honey and the honeycomb." Why is it so precious? Because we are a fallen race of people, and because sin has clouded our minds. We need it, says David, because, "Who can understand his errors?" Without the Bible we can't really know God, and we can't really even know ourselves!
Our response to all this should be great thankfulness for all of God's revelation, both natural and written. It reveals Him, and it reveals our errors. Oh how we need it! In view of it we should sing with David, "Cleanse me from secret faults. Keep back Your servant also from presumptuous sins (the ones that aren't "secret"). Let them not have dominion over me!" When God answers this prayer, then - and then only - can we go on to sing, "Then I shall be blameless, and I shall be innocent of great transgression (great because it is against a great God)."
Along with David, our final response to God's Book should be, "Let the words of my mouth and the meditation of my heart be acceptable in Your sight, O Lord, my strength and my Redeemer!"