This text explores the ontological question of the nature of "true being", defining it through the principle of unity. A true being must be unified and clearly distinguished from other beings. The author emphasizes that this distinction should not be understood merely as an external or physical boundary. The key element in unifying multiplicity into a single "one" is the emergence of "interiority". It is this interiority that allows for a breakthrough beyond the pure externality of objects, creating a space where the closure of things is transcended. Only through this internal dimension can mutual intersections and transitions occur between individual beings, moving beyond purely external relationships. The paper presents the thesis that true being is not merely an isolated object but a dynamic unity with a profound internal world that defines its integrity and its capacity for relating to the surrounding world. This interiority is an essential condition for multiplicity to become a true, unified being.