This text presents a philosophical analysis of perception and the nature of beings, distinguishing between the immediate experience of "something" and the subsequent mental construction of individual "things." The author argues that perception is not a passive process but an active performance of the subject, requiring comparison with broader experience. While physiology interprets these processes as mere automatisms, the text emphasizes the necessity of assuming a form of subjectivity wherever "reactability"—the capacity to react to stimuli—is present. This trait is inherent to all "true beings," not just higher animals. The critique of the physiological approach lies in its heavy reliance on objectification, which overlooks the unique activity of the subject. Relationships between subjects precede their interpretation as discrete objects, suggesting that interaction and reactivity are primary levels of existence, whereas perceiving the world as a collection of "things" is a secondary cognitive result. Ultimately, the reflection aims to redefine the subject through its active engagement with its environment and other subjects.