For millennia, the enigma of the world of Ideas or Forms, which Plato suggested and advocated, has been challenging the most prominent thinkers of the humankind. This paper presents a solution to this problem, namely, that an Idea in the Platoʼs sense can be interpreted as a scientific object called a structure. To validate this statement, this paper provides rigorous definition of a structure and demonstrates that structures have the basic properties of Platoʼs Ideas. In addition, we describe the world of structures and prove its existence. This allows us to resolve the controversy between Plato and Aristotle concerning Ideas or Forms and to build a scientific interpretation of the metaphor of the Divided Line, which Plato uses in his theo...