The article is devoted to analysis of multiple structure, which appears as the origin of complexity: of its mani- fold and multidimensionality. Representation of multiple character of structure, which is virtual and being realized in actuality only partially - is the initial presupposition of the research. This feature makes relations differential, mutually determinable. Mutual determination of relations represents a qualitative difference, which cannot be objectified. This difference is really existing, not actual, but virtual. Virtual is presented here as real, having full completeness of existence. It is affirmed in the article that virtual and potential are of different nature. Potential is a hypothetic similitude of an actually existing form, object. Virtual is not linked to an actual, though it deter- mines the borders of the latter. Reality of virtual and multiple architecture of structure exclude their determination through basic identity and its reduction to single elements, qualities or relations.