The holiness of the creatures of God is one of the great elements of his happiness. The doctrine that the happiness of God rests for its support, in part at least, upon the holiness of his creatures, is one of great interest to men. It furnishes a new motive to holy effort. Everything we do has its correspondent result in the divine mind. There is not a throb in our bosoms, beating in the direction of pure and universal love, which does not excite joy in the bosom of our heavenly Father. It is not more true that angels rejoice, than it is that God rejoices, over every return from sin and every advance in holiness.
It is hardly possible to conceive of a higher result in the destiny of man than that which thus contributes to the happiness of God. The thought, therefore, should animate us in all our efforts, namely, that God sees us; that he takes an interest in all our acts and feelings; and that when we are good our Father is happy. The light of our little star goes back to its parent sun. The small wave of our little fountain swells the broad billow of the mighty ocean. Can there be a higher motive to action than this?
Then let us labor on. God works. Let us work with him. Let us suffer; if needs be. Yea, let us rejoice in suffering; but neither in toil nor in suffering trusting to ourselves, but rather "looking unto Jesus, the author and finisher of our faith; who, for the joy that was set before him, endured the cross, despising the shame, and is set down at the right hand of the throne of God."
— edited from A Treatise on Divine Union (1851) Part 7, Chapter 12.