The greatest joy is joy in God. This is plain from Psalm 16:11: "You [God] will make known to me the path of life; in Your presence is fullness of joy; in Your right hand there are pleasures forever." Fullness of joy and eternal joy cannot be improved. Nothing is fuller than full, and nothing is longer than eternal. And this joy is owing to the presence of God, not the accomplishments of man. Therefore, if God wants to love us infinitely and delight us fully and eternally, he must preserve for us the one thing that will satisfy us totally and eternally; namely, the presence and worth of his own glory. He alone is the source of full and lasting pleasure. Therefore, his commitment to uphold and display his glory is not vain, but virtuous. God is the one being for whom self-exaltation is an infinitely loving act. If he revealed himself to the proud and self-sufficient and not to the humble and dependent, he would belittle the very glory whose worth is the foundation of our joy. Therefore, God's pleasure in hiding this from "the wise and intelligent" and revealing it to "infants" is the pleasure of God in both his glory and our joy.
John Piper, The Pleasures of God: Meditations on God's Delight in Being God
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