We are not born for our own sake; we are born for the sake of others. That is, we are not born to live for ourselves alone; we are born to live for others. Otherwise society would not be cohesive and there would be no good in it.
There is a common saying that we are all neighbor to ourselves. The body of teaching on goodwill, however, shows how we should understand this. We are all supposed to provide ourselves with the necessities of life, such as food, clothing, a place to live, and many other things that are required by the civic life in which we participate. And we provide these things not only for ourselves but also for our loved ones, not only for the present but also for the future. If we do not provide ourselves with the necessities of life, we are in no state to practice goodwill, because we lack everything.
How we are to be neighbors to ourselves, however, can be shown through the following analogy: We should all provide our bodies with food. This has to come first, but the goal is to have a sound mind in a sound body. We also ought to provide our mind with it food, that is, things that build intelligence and judgment; but the goal is to be in a state in which we can serve our fellow citizens, our community, our country, the church, and therefore the Lord. People who pursue this goal are providing well for themselves to eternity.
These points make clear what is primary from the standpoint of time and what is primary from the standpoint of purpose. What is primary from the standpoint of purpose is the true overall goal.
This situation is like people building a house. They have to lay the foundation first, but the foundation is for the house, and the house is for living in. People who hold being neighbors to themselves as their first and foremost objective are like people whose main purpose is building the foundation rather than living in the house. Yet living in the house is the primary and ultimate purpose overall; the house and its foundation are only a means to an end.
from True Christianity, Section 406