Some spirits who thought themselves better informed than others claimed that in the world they had held to the belief that heavenly joy consisted solely in praising and glorifying God, and that this was an active life. They have been told, though, that praising and glorifying God is not an appropriate kind of active life, since God has no need of praise and glorification. Rather, God wants us to be useful to each other, to do the worthwhile things that are called works of charity. However, they could not connect any notion of heavenly joy with thoughtful good deeds, only a notion of slavery. The angels, though, bore witness that it was the freest life of all because it stemmed from a deep affection and was invariably accompanied by an indescribable pleasure.
from Heaven and Hell, Section 404