The thesis follows the development of the As-Structure as it is presented in Heidegger's Logic (GA 21) and shows that this abstract structure has been developed based on Brentano's Psychology 1 and Husserl's Logical Investigations. I describe how the As-Structure develops from the Brentano's distinction of physical and mental phenomena. The mental phenomena represent the basic sphere of our recognition, and the knowledge of the object as it is immanent to them. The object represents a stable counterpart to the course of experience (Objekt - Erlebnis relation). Therefore, only in the mental phenomena the object is being experienced just as it appears. This is the standpoint of Brentano, and it is adopted by Husserl who explicitly divides the structure of an intentional act into its constituents; the meant and the given. The object is accomplished when it is carried out by the intentional act. When the relation between the meant and the given is fully congruent, the given is given just as it is meant. Heidegger elaborates on this given as meant structure by transferring it outside the sphere of consciousness. He claims that the As-structure is the abstract constitutive element of the relation between the human (Dasein) and the thing; what is being encountered in the world is always given as something..