The text discusses the emergence of biology as a scientific discipline within the context of ancient Greek philosophy. The central theme is Aristotle's distinction between mere appearance or opinion (doxa) and true knowledge (episteme). Genuine knowledge requires a profound insight into truth, referred to as theoria. The author analyzes how early thinkers dealt with the phenomenon of change and motion, which was crucial for the study of nature (peri physeos)—the processes of birth, growth, and decay. Aristotle was the first to recognize the possibility of scientific investigation even for changing beings, provided their motion is natural (physei), meaning it is driven by an internal principle. By defining the internal dynamics of living organisms, he laid the foundations for biology as a legitimate science. The work illuminates the transition from general philosophical reflections to the systematic study of living nature, emphasizing the significance of internal change for understanding the essence of life. This historical-philosophical analysis shows that the scientific grasp of biology is inseparable from deeper ontological questions regarding motion and stability.