Psalm 19:7-8 The law of the Lord is perfect, reviving the soul; the testimony of the Lord is sure, making wise the simple; the precepts of the Lord are right, rejoicing the heart; the commandment of the Lord is pure, enlightening the eyes.
If I was standing around with Stephen Hawking and Brian Cox and someone asked a physics question, it would be ridiculous to think that I would speak up with an answer. Or if I'm at a meal with David Beckham and someone asks what it feels like when the ball hits the back of the net, I shouldn't be the one who dives in with a detailed description of the (own) goal I scored at last week's 5-a-side! But we seem quite happy to do that with God. We treat the Author of Life as someone who can maybe offer a bit of advice on the way we live, but other than that we think we've got life covered. Despite our limited experience of it, we treat ourselves like experts on our own life. The problem with that attitude is that, as proverbs says, the way that seems right to us leads to death! We are self proclaimed experts on life but we are actually walking around in darkness with our eyes closed.
God's revelation to us - about himself, ourselves and how life works - is perfect, sure, right and pure, unlike the imperfect, uncertain, faulty and biased ideas we invent for ourselves about how we think the world does or should work. It's God's word that gives wisdom and opens our eyes to see things as they really are, and that news - the depths of our sin and the wonders of his grace - revives our souls and causes our hearts to rejoice.