However, the Psalmist also acknowledges that while creation might be a word from God to us, it is not the whole conversation. We are not left to make every inference about God from creation alone. Indeed, though the Psalmist doesn't explicitly state it here, any faithful Israelite would certainly see that as a quick path to idolatry. We need something more.
So after praising God for God's revelation in nature the Psalmist gives thanks for God's revelation in God's law. This law the Psalmist describes as perfect - that is, it is complete, blameless. It brings wholeness and clarity to what would be an otherwise fuzzy and potentially misleading picture of God's character. It tells us what we could never surmise about God from creation alone. We are told that this law revives the soul, makes the simple wise, gladdens the heart, brightens the eyes, endures forever, and is altogether righteous. Therefore, it is to be desired more than the finest gold and the sweetest honey. The law is not a burden or a list of rules. It is something to be cherished and enjoyed because it reveals God to us. Without it, we would be left worshiping dumb idols of our own making.
The final verses of the Psalm turn from words of praise to words of request. The Psalmist recognizes that he, even with the law as a guide, can not discern his own faults (v.12) so the Psalmist prayer is for forgiveness for when he does sin and for safe keeping from the ways of sin. In v. 13:
"Keep back your servant also from presumptuous sins; let them not have dominion over me! Then I shall be blameless, and innocent of great transgression."This is a telling request for in it is a recognition, that even the law, for all of its perfection and revelation of the character of God, is not itself able to prevent the Psalmist from sinning. The Psalmist not only needs God's law to know what is right but also needs God's power to do what is right. As the Psalmist says "let them (sins) not have dominion over me!". There is a recognition that even with the law before us and even as we confess that it is a good and perfect law, the law itself is still powerless to defend us against sin. We need God himself to act on our behalf in order to keep us blameless.
As Christians, we confess that Jesus Christ and the Holy Spirit are that act of God on our behalf. It is precisely this idea for which the apostle Paul argues in Romans 5-8. By his death and resurrection, Jesus has inaugurated a new age in which we are not only forgiven but in which the power of sin has been broken so that it no longer has dominion over us. We are now empowered by the Spirit to fulfill the law of Christ so that the words of our mouths and the meditations of our hearts are indeed acceptable to the Lord who is our rock and redeemer.