An awesome piece from John Piper:In Luke 2:10-11 we hear a word from God to the shepherds: "But the angel said to them, 'Do not be afraid; for behold, I bring you good news of great joy which will be for all the people; (11) for today in the city of David there has been born for you a Savior, who is Christ the Lord.'" Now what was the aim of this word? It was, at least, to produce joy. "We bring you good news of great joy." Huge joy! In other words, the truth about Jesus – that he is a Savior and Messiah and Lord and that he was born in the prophesied city of David – this truth was to inspire great joy (and it did, Luke 2:20). And when it did, who got the glory? Jesus did. He is Savior, Christ, Lord. This is what the Word revealed, and this was what inspired the joy. Therefore the change brought about by the Word gets glory for the truth of Christ in the Word.
But suppose the shepherds were out in the fields keeping watch over their flocks by night and suddenly the Holy Spirit came upon them and filled them with great joy with no news at all. No Word. No revelation. Only the feeling of joy. Who would be honored for that? Nobody, except maybe the Shepherds for being so resilient against the cold winter's night. How would it honor and glorify Christ if the Spirit created in us all kinds of good feelings and good resolves with no reference to Jesus and his cross and resurrection and the great acts of God in history? It wouldn't. So the way the Spirit brings about change in our lives is to quietly enable us to see in the Word the beauty of Christ and his ways. Then our motivation consciously flows from the truth about Christ, and he is glorified, and the Spirit remains the behind-the-scenes power that opened our eyes.
So you see why my main point says, prayer and meditation are as inseparable in living the Christian life as are the Spirit of God and the Word of God. Prayer is the human act that corresponds to the Spirit of God, and meditation is the human act that corresponds to the Word of God; and just as Word and Spirit are inseparable in how God changes us, so prayer and meditation are inseparable in how God changes us.