...and this is where I think Piper goes off the tracks. I listen a lot to Piper and have much of his work but it's too "me focused". In the end, if your focus is your own joy, you've made yourself God. Yet, on the other hand, the Scripture seems to indicate that if you pursue God in Christ and all He offers, you will find joy as a byproduct. That seems to be the scripture balance.
Dr. Gonzalez, I appreciate your desire to be careful on this matter. Thank you for clarifying where you think the problem resides. I think the solution to the tension is not far off. If you aim at your own happiness, at your own enjoyment of God, you are not likely to get it. This is a point that C.S. Lewis has emphasized well. John Brown is speaking of our own thoughts and attitudes, at what we aim at. Hence the phrasing of the question, "Is our own delight, etc." If my goal is my own happiness I will lose that and will not actively glorify God. If my goal is to glorify God, I will find that God's glory and my enjoyment are blessedly inseparable.