By the science of national,(130) or Political Economy, we understand the science which has to do with the laws of the development of the economy of a nation, or with its economic national life. (Philosophy of the history of Political Economy, according to von Mangoldt.) Like all the political sciences, or sciences of _national life_, it is concerned, on the one hand, with the consideration of the individual man, and on the other, it extends its investigations to the whole of human kind.(131) National life, like all life, is a whole, the various phenomena of which are most intimately connected with one another. Hence it is, that to understand one side of it scientifically, it is necessary to know all its sides. But, especially, is it necessary to fix one’s attention on the following seven: language, religion, art, science, law, the state and economy.(132) Without language, all higher mental activity is unthinkable; without religion, all else would lose its firmest foundation and highest aim. Through art, alone, do all these sides attain to beauty; through science, alone, to clearness. Law arises, the moment conflicts of will become inevitable and an adjustment is desired. The state has to do with them, in so far as they have any external force or validity. Indeed, there is no human relation, not even the highest and the sweetest, but has its economic interests. It is, therefore, natural, that each of the sciences which relate to these various regions of human life should, in part, presuppose all others, and, in part, serve as a basis for them.(133) But in the midst of this universal relationship, it is easy to see that law, the state and economy constitute a family, as it were apart and more closely connected. (The social sciences, in the narrower sense of the expression.)