Both the ancient Chinese and Greeks from around the fifth century B.C. to around third century A.D. recognized the immense impact that music has on the development of one's personality, and both regarded it as crucial in the cultivation of proper disposition in youth. Music's power over one's ethos--that is, human disposition--was emphasized by Plato and by Chinese authors of various documents. Music in both cultures was considered an important means for a proper education and a powerful tool for cultivating and ruling over the people of a nation-state. In both cases, the power of music was further connected to the way the universe works. Yet the reasoning strategies in the two cultures differed enormously. Observing how the two remote cultures conceived the relationship between music and the ethos may give insight into music's role in aesthetic education among modern listeners. This study investigates how the power of music was understood and explained in the two ancient cultures and compares their explanations and reasoning strategies.