The Word of God is Life. When we meditate on the Word of God, we are taking in life. This is the true essence of life in the entire creation. There is no life anywhere. Science could not know where life is. It is the breath of the Almighty the gives all creation life.
The entrance of the Word of God gives light. There's no light outside the word of God. We are enlightened when we open our hearts to allow the word of God to illuminate our being. The light of the Word of God brings progress and success to us.
Meditating on other materials outside the Word of God is a mistake. The laws of men shall fail. The theories of men shall fail. It is the word of God that shall endure forever.
We should only meditate on the word of God. We should allow the power of God to work in our lives so that we can become what God wants us to become. It is the word of God that will create in us the kind of life which God wants us to life.