For Empedocles (490-430 B.C.) the four elements mentioned above (water, air, fire and earth) are altogether the fundamental principles of the Universe. The scheme of Empedocles is worth remembering because it will be influencing our further investigations. According to Empedocles thus, "four are the roots of everything, four are the forces of nature or states of matter."

                                                                                                                       

State of matter or of elements

fixed

volatile

wet

Water

Air

dry

Earth

Fire

It is not without reason that we speak more precisely concerning these first attempts of TOE. They show that since man tried to think independently and to liberate himself from religious and mythological beliefs, he tried simultaneously to understand the Universe and to create a comprehensive and coherent theory explaining the totality of the surrounding reality. These are not yet physical approaches (physical in the sense of contemporary physics) but nevertheless they are rational and philosophical approaches, and in a certain way, materialistic theories trying to justify the Universe and to explain it, using one short and understandable physical (material, non-spiritual) principle. Behind these attempts, we can notice another kind of temptation, which we can call "looking up God's sleeve". Understanding the Universe, its composition, its way of working, means to create it, or re-create it, even theoretically, that is, only on paper. So it is not surprising that nowadays theoretical physicists and cosmologists cannot avoid such a temptation.

Plato and Aristotle also created their own philosophical TOE. For Plato, the condition sine qua non of understanding the structure and the construction of the Universe is the dialectical ascension into the world of pure ideas. Achieving this ascension means reaching the highest level of knowledge (gnosis or episteme) and it gives the philosopher the full insight into the nature of the Universe through the reminiscence of the world of pure ideas. This is only possible on one condition, namely if man liberates himself from the chains binding him to material reality, to the temporary world of shadows. The liberated man is able to reach the ideal and perfect world, where perfect and full knowledge is attainable. In this sense, Plato's TOE is possible only for mystics, in an almost religious revelation. TOE can be created or understood just at the top of the laborious ascension through the steps of knowledge (from doxa through the pisitis and dianoia to the gnosis-episteme.)

Aristotle tries to pull down Plato from heaven to earth and to show that the world is knowable not through the ideal world but in the realistic and philosophical vision of the nature of this material world. Aristotle's explanation of the Universe, though nowadays archaic, nonetheless still remains a good example of a rational attempt towards the understanding of reality, based on what nature itself reveals to us through sensual knowledge. The world is not a shadow of ideal reality, but it is reality itself, knowable by our senses and explainable by reason, not by reminiscence of what we knew about it in the ideal world.

To create TOE, we have to know everything which is accessible to our senses and to generalize, to summarize everything to the most fundamental and general principles. For Aristotle, this is the theory of material being which is temporal, spatial and changeable. Understanding this being and its principles gives us the insight into the nature of the Universe and into the most fundamental principles of existence.

Aristotle develops his metaphysical theory of ontological constitution of being, but he is also the first to show the way to modern physics, accentuating the phenomena of motion and the necessity of its study. It is true that in his metaphysical theory of motion he is talking rather about the qualitative aspects of motion, but the quantitative aspects of his theory (although false) are the foundation of classical mechanics. From his physical theory of motion, there is only a small step to be taken towards modern physics although for this step science and philosophy will have to wait for centuries. Nevertheless, Aristotle should be recognized among those who have attempted to understand the Universe as a whole in a rational way and to build up a philosophical TOE. As for Plato, the knowledge of idea was the main point to understand reality; so for Aristotle, the knowledge of material reality opens the way for us to understand the totality.

So, in ancient philosophy we already have examples of the construction of the TOE, which will be developed (in further history) into two different kinds of theories. On the one side we will have a continuation of the research into the philosophical explanation as a whole, while on the other (starting from Fifteenth and Sixteenth Centuries) the autonomization of the physical attempts of constructing the TOE based on the natural sciences, especially physics. In the process of development of the tools of physics, the philosophical attempts will be put on the periphery of human knowledge because of their insufficiency or inaccuracy. The qualitative aspects of philosophical ideas will gradually be replaced by the qualitative aspects derived from physics. In this way, natural sciences, with physics and cosmology at the top, become primary. Nevertheless, we cannot neglect the value of those philosophical attempts present in antiquity. They forged ideas and concepts. They tried to present the rational understanding of the Universe as a whole, which was attainable for humanity at that time.

It is thus comprehensible that man would like to understand the Universe and its structure, and his place in it in each era. It is understandable that he would like to understand origins; the origin and the destiny of the Universe as well as his own. So man would desire to understand the Universe creating the Theory of Everything, literally "everything." Is there something intrinsically evil in this attempt? Are such attempts not an expression of the fundamental human desire to discover his non-accidental and non-transient nature? To understand, to know, means to govern, to take his own future in his hands and to be a non random result of a blind game of the forces of nature. Of course, such a desire can lead us to boldness, arrogance, atheism and rejection of God who will be replaced by arrogant reason. Indeed, in the history of philosophy, we encounter such events.

On the other hand, those desires and researches can lead to humility and to the deepening of faith, to the acceptance of the truth that the final explanation and justification of everything can be found in God. This is the place where the religious truths that are "ex-definitione" TOE, can meet the rational or even the scientific attempts of TOE. I am certainly not in favor of a concordant idea of mixing scientific knowledge with philosophy or religion. But, from another point of view it is also not acceptable to bring natural sciences and religion into contradiction. <CITY><PLACE>Saint Augustine</PLACE></CITY> did not err speaking of the necessity of understanding in order to deepen the faith "intellige ut credas". He also, underlines the necessity of faith in order to better understand "crede ut intelligas". Thus faith is not a contradiction of rational understanding and vice versa. Personally, I am deeply convinced that TOE's are the basis on which science and faith can meet each other with mutual respect and show together the deepest meaning of the existence of the world and ourselves.

In the second part of this article, I would like to show how TOE's were further developed in the history of philosophy, and particularly how they became the domain of natural sciences.