How can an element change form and become something entirely different? These questions, among other things, concerned the so-called Eleazan philosophers.
Parmenidis believed that everything that existed existed forever. This idea was widespread in ancient Greece. They considered it almost self-evident. Something can't be born from nothing, Parmenides said. And everything that exists can not disappear and be lost once and for all.
He saw, of course, that everything was constantly changing in nature. With his senses he perceived these changes of things. But he could not bring them into harmony with what his logic dictated. As he was in a dilemma, if he had to trust his senses or his logic, he decided in logic. As a philosopher, he considered his duty to reveal all the "illusions" that gave us a misconception of the world and reality. This strong belief in human logic took the name rationality. Parmenides argued that the unity of things in the world is not based on a common underlying physical substance but on their own entity. The basic position of parmenid thought is that "the being is unborn and irrational , complete and united, unperturbed and perfect"
At the same time as Parmenides, Heraclitus lived and considered the changes as the most basic and most important feature of nature. We can say that, unlike Parmenides, Heraclitus showed confidence in his senses and what they were saying to him. "Everything flows" said Heraclitus. Everything is in motion, and nothing holds forever. Heraclitus also noticed that the world is sealed by constant contradictions. Both good and evil have their place in the whole and are just as necessary, Heraclitus said. Without this unstoppable game between opposites, the world would cease to exist. He used the word "god," but he certainly did not mean the gods of myths. For Heracleitus, god - the divine element - is something that embaraces the entire world. God is revealed to man through the constant alteration and change of nature. Instead of the word "god", Heraclitus uses the ancient Greek word "reason," meaning logic. Even if we humans do not always think the same way, even if our logic is not always the same, Heraclitus believed there was some kind of "global logic" that directs everything in nature. This "world logic," the "mind of the universe," governs everything, and all people must respect its dominance. In all the alteration,changes and contradictions in nature, Heraclitus saw unity, completion. This "something," which is found in everything and is the foundation of everything, was called be heraclitus "god" or "reason." Heraclitus believed that people's behavior was judged by the truth of reason, so people have to understand it, be perfect in it, and live according to the secular law.
Parmenides and Heraclitus were somehow at the two opposite ends. Parmenides's logic found that nothing could change, while the experiences of Heraclitus found, with the same certainty, that everything in nature underwent constant changes.
Which was right?
Empedocles thought that they were both right about one point of their thought, but wrong with regard to the second one. All the difference arose from the fact that the philosophers regarded the self-evident starting point of their thinking as the existence of only one primary element. If that was the case, then the abyss between senses and reason would be unbridgeable in the centuries. Empedocles proclaimed that the universe is synthesized and decomposed by four unchanged "rhizomes": water (Nistis), earth (Adongeus), air (Hera) and fire (Zeus). Every genesis and decay is the result of mixing and separating the four rhizomes in different proportions at a time, depending on the form of what is born or decayed. Thus the being (rhizomes) does not change (view of the Elaites), but also genesis and decay are real processes (view of the Atomic).
So, it is not true that "everything" is changing. In essence, nothing changes. Simply, four elements are joined together and separated again, to merge again in a different way. One question, however, remains: what is it that pushes these elements to unite together, creating a new life? And what is it that makes sure that this "blend" dissolves again?
Empedocles believed that there are two different forces in nature. These forces called them Filotita and Neikos. Filotita, love, is the power that unites the elements and creates new "blends". Neikos, conflict, is the power that separates them again. This is something important to note because, even today, science distinguishes key elements from natural forces. Modern science claims to be able to explain all natural phenomena with the help of interactions between the basic elements and some natural forces.