What does Psalm 19:8 mean?

Whatever actions the Lord commissions His people to do are right. His charges reflect His righteous character, and they give joy to those who obey them. Jesus promised that obedience to His commands would bring joy (John 15:10–11). The commandment of the Lord is His prescription or direction for doing His will. It is described as "pure." God's Word is undefiled and produces a pure life in those who obey it. In 2 Timothy 3:15–17 the apostle Paul refers to God's Word as "sacred" and able to make a person "wise for salvation" and capable of leading a life that honors God.

Those who reject God's Word and depend on their own wisdom for a meaningful life are perishing. They will someday regret their choice (Revelation 20:11–15). First Corinthians 1:19 says, "It is written, 'I will destroy the wisdom of the wise, and the discernment of the discerning I will thwart." With these words, David credits God's Word with brightening the eyes of those whose eyes are dim. In other words, Scripture enlightens our minds to understand God's Word and His will.