Psalm 19 is fairly well known for its two sections. The first part is about how Creation reveals the existence and nature of God. This is referred to as "General Revelation". The second revels in the wisdom of God's Law. This is called Special Revelation, because God has revealed things not otherwise knowable. The two sections are generally considered separately, each for the point made in that section. But the two sections are part of a single, unified, composition.
This might seem odd, almost as if two disparate topics got spliced together, but I think God is trying to tell us something about both kinds of revelation. General Revelation, Creation, shows much about God - what kind of God could and would create something of the scale of the universe. But that isn't very clear or detailed. Special Revelation, God's word, is what General Revelation is not and cannot be - specific, clear, and detailed. But God gave mankind General Revelation, Creation, to enrich what His word tells us.