The people make up the nation. No country can seriously claim greatness yet when you come to visit it is plagued with streets reminiscent of a third world country. Individual accomplishment signifies individual greatness, meaning a nation isn't great because one or two of its peoples make a significant contribution to a specific field. Greatness of a nation is reflected by the general welfare of its people.
I think that when one tries to categorize the people into sections that is just foolish because the artists, scientists, and the rulers are the people and therefore all the people should be the surest indicator of the greatness in which their country possesses. But by no means should the artists and scientists not get more credit because they should.
One of the reasons people live in decent standards in First World nations is because of the great Strides many countries have. Germany, Italy and Scotland have amongst some of the world's highest standards of living because of the brilliance of many architects, planners, capitalists, etc. Without that there isn't a prosperous nation.
I reckon what makes a nation great, is how much it influences other nations in many regards. Then the amount of values created by nation in many areas from art, science, human relationships to Technology can be interpreted as its power and importance. It can also be predictable that people living in such nation should benefited of welfare, wealth and happiness owing to the obtained achievements, however, it is not only the achievement of prosperous individuals can make the life situation better, but also the management of ruler, their politics and many other related factors affect this issue too. There is the possibility that people of a nation which was great in the past suffer from poverty, illiteracy or many social problem issues these days, like Rome, Greece, Iran and Egypt...