In its attempt to come to grips with the nature of the human mind idealism employs such terms as "e;pure self,"e; "e;transcendental apperception,"e; "e;pure con- sciousness"e; and so on. What do these terms mean? What do they refer to? Pro- visionally, at least, the following answer could be satisfying: such and similar expressions are purported to capture a very special quality of human mind, a quality due to which man is not simply a part of nature, but a being capable of knowing and acting according to principles governing the spiritual realm. In the first chapter of the present study the author attempts to bring the idea of "e;pure Ego"e; down to earth. By analyzing Kant's concept of pure appercep- tion - the ancestor of all similar notions in the history of modern and contem- porary idealism - the author concludes that certain functions and capacities attributed to pure apperception by Kant himself imply the rejection of the idealistic framework and the necessity to "e;naturalize"e; the idea of pure self. In other words - and Kant's claims to the contrary notwithstanding - pure ap- perception cannot be conceived as superimposed upon man viewed as a part of nature, as a feeling and a sensing being. The referent, as it were, of the expres- sion "e;pure self' turns out to be something much more familiar to us - a human organism, with all its needs, drives and dispositions.