A system of thought, like a house with brick and mortar, has a foundation and a superstructure. It is the superstructure which attracts more attention, applause or censure. The foundation remains unnoticed. Yet it is the foundation which hides the secret sources of nourishment of the entire structure. This foundation consists of a group of basic concepts and assumptions which the thinker brings into play. The greatness of a thinker lies in the originality and strength of these concepts and assumptions. The mediocre build on nothing new.