I talked with some spirits who thought that heaven and heavenly joy consisted of being important; but I told them that in heaven the greatest is the one who is least. This is because people are called “least” when they have no ability or wisdom and do not want any ability or wisdom on their own, but only from the Lord. This kind of “least person” has the greatest happiness. And because such people do have the greatest happiness, it follows that they are the most important, because this is how they have all their capability and the most wisdom of all—from the Lord. Further, what is being the greatest if not being the happiest? The greatest happiness is what powerful people are seeking with their power and what rich people are seeking with their wealth.
I went on to say that heaven did not consist of wanting to be least in order to be greatest. People who do this pant and long for greatness. Rather, it means a heartfelt wishing better for others than for oneself, and serving others for the sake of their happiness with no thought of reward, simply out of love.
from Heaven and Hell, Section 408