To evaluate the claim, we may first make clear the definition of "a great nation". If we regard  a country as great only in terms of its high level of technological, art or economic and scientific development, it is no doubt that its rulers, artists or scientists may represent its greatness, but on the contrary, if the greatness on erected on the basis of the nation's overall fulfiment and how its citizens feel about themselves and the government, the general welfare of its people is surely a better yardstick to measure the country's greatness. While the standards are various, I hold the view that, the latter is more objective and people's general welfare is a more measuring method.
It is undeniable that the preeminet artists and scientists can tell us more about a country's highest and most advanced development in a specific country. Take the ancient China during the Tang Dynasty as a compelling illustration, the whole nation was then a prosperous entity, and the poets and writers are prolific due partly to the booming of the economy and the relatively amiable political atmasphere. In addition, the literature achievement of that period is  the highest in the history of ancient China, as well as the greatness of the nation. Nowadays, when people talk about the prosperity of China, they still mention the Tang Dynasty.
However, the highest level of a nation can not reflect its overall greatness in some other conditions. For example, in the industrial revolution of 18 century France, the machinery and manufacturing field are so booming that France, in combination with its neighbor-the Great Britain-constitute the most advanced technological level and the wealthiest kindom in the world,  while in contrast to the prosperity of the whole nation, its low-class citizens generally lived miserable live, working long hours and were kept in a low wage level. Apparently, such France can not be called a great nation.
Compared to the artists and scientists, the general welfare of the common people is another good choice to measure the development of a country. Not only because the objective of a government is to facilitate the life of its citizens, but also for the reason that the what common people view their country is able to cover all aspects of the administration of the country, including the economy, the policy, the jurisprudence, as well as the educaion, the art and the communication. Just witness the people's life in several northen Europe countries like Denmark, Norway and Switzerland, where the general welfare of the whole society is so high that people all possess a viable job and a stable health insurance. Even though there are no prodigious leaders and artists or scientists that may change the world economic systems or impress the the art realm, we have to recognize that they are all great nations.
From what has been discussed above, we reach the conclusion that the achievement of a nation's rulers and artists or scientists can be a yardstick to weigh the development of the nation, but it may not be the most exact way. Considering the objective of a goverment,  the general welfare of its people can be a better mearsurement for the weighing of a country's greatness.