 Completing ideal theory first, Rawls says, yields a systematic understanding of how to reform our non-ideal world, and fixes a vision (mentioned above) of what is the best that can be hoped for. Once ideal theory is completed for a political sub-domain, non-ideal theory can be set out by reference to the ideal. For instance, once we find ideal principles for citizens who can be productive members of society over a complete life, we will be better able to frame non-ideal principles for providing health care to citizens with serious illnesses or disabilities. Similarly, once we understand the ideal principles of international relations, we will better see how the international community should act toward failed states, as well as toward aggressive states that threaten the peace.