Heraclitus is usually recognized as a philosopher who believes in the motion and becoming of all things. He also maintains that there is a kind of conflict among opposites, which finally leads to their unity. However, not much attention is paid to the fixed principles that exist in his philosophy. The most important of all of them is logos, which is also referred to by some other terms such as fire, God (theos), etc. Logos is a fixed divine principle which establishes harmony among all things, and a philosopher is an individual who hears the words of logos and acts accordingly. Therefore, it can be said that, in addition to the becoming of worldly things, Heraclitus also speaks of unity and consistency in his philosophy.