Early in the sixth century B.C. first attempts were started to understand the world in new ways. Until then the mystical world of Homer was explained through tales which put the experiences of the heros in context with universal principles. The adversities of the heros daily life were combined with tales about the Gods and tried to show parallels to the viewers own life experience.

Looking at the world in a more scientific way was the first step towards a new view of the world but in the beginning there were still ties to mystical elements. About one century later Parmenides of Elea tried to expain the world through pure rational logic. This was the first time that a differentiation was made between rational truth and sensual perception. Parmenides separated static material substance from a dynamic regulatory vital force. These two aspects had always been seen as separable until then.

Leucippus and Democritus developed the first models of reality which explained everything in material terms. Miniature particles (atoms) were the building blocks of life and worked like a mechanical device - no vital force was required in their model, it was purely based on matter.

Sophists

In the second half of the fifth century B.C. the tradition of the Sophists emerged. As travelling teachers they were worldly, liberal minded humanists. Their thinking was shaped by rationalism and they evaluated every theory or opinion by its usefulness. At that time various theories about the nature of reality were persued, most of them were contradicting each other and often had not much in common with daily life experience. The Sophists criticized the escapist character of these theories and argumented that each person had his individual experiences and individual truth. Trying to define an objective reality was pointless to them. Since the Sophists rejected to persue objective truths, they made an effort to establish public schooling in rhetoric and logic. Their ambition lead to the creation of a system of instructions - the paedeia - which became the public education system of Ancient Greece.

Thus old certainties became increasingly uncertain, but there were no new certainties to replace them with, because the philosophy of the Sophists denied humans the capability to conceive any objective truths.

Socrates

During these turbulent times the philosopher Socrates was growing up. During his education in the natural sciences he resented the contradictory nature of the theories he was taught. Since they contributed more to confusion that to clarity in his view, Socrates turned his back on science and cosmology and persued ethics and logic as new subjects. Contrary to Sophist belief Socrates assumed that there was an objective truth but that it had not been discovered yet. According to Socrates, the acknowledgement of one's own ignorance was required at the beginning of the philosophical path but it was not its destination.

Socrates taught that all human beings were in persuit of happiness. Happiness could only be achieved if a person's way of life was in accordance with the nature of his soul. Happiness thus was not a result of external circumstances but a result of one's lifestyle. In order to live a truly good life, a person needed to know about the nature of goodness. Thus it is required to act according to reason and to discover the virtue behind each of one's actions.

With his dialectic method of inquiry Socrates developed one of the core columns of Western thinking : During a discussion with another person Socrates evaluated their statements and the hidden assumptions these statements were based upon. These assumptions were then rigorously taken apart and questioned in order to drill down to the truth. But Socrates method was not only targeted at analyzing the assumptions of other people : Practicing philosophy was about constantly analyzing one's own thoughts critically. True knowledge was something that could not be learned by listening to other people it had to be personally attained.

With his habit of constantly taking other people to task, Socrates was not too popular among certain circles and he was increasingly seen as a undermining element of the existing social order. Thus two Athenian citizens accused Socrates of godlessness and of having a bad influence on the youth. Socrates was put on trial. Even though he could have fled from the city, Socrates stuck to his principles and decided to die for them. Through being sentenced to death by drinking poison Socrates became a martyr of the philosophic ideal. He paid for his attempts to improve the Athenians' sense of justice with his own life.

Plato

Plato was a student of Socrates and continued to develop his philosophy. For Plato the highest truth was not purely of a material nature. He taught that every material object also had a transcendental aspect to it, which could be perceived by any skilled philosopher. Besides the aspect visible to the physical eye this transcendental aspect could only be perceived by a truly loving person. It was required to be deeply moved by a universal passion to reunite with the divine. The immortal soul was in contact with the divine prior to birth but lost this connection due to amnesia when entering the physical body. Plato saw it as the task of any philospher to help in the process of remembrance of the transcendental aspects in order to attain a direct inner knowing of the real causes and reasons for all events and things.

Plato recognized that the world contained a required amount of error and irrationality. He associated the irrational with the material world and with the lustfulness of the insticts, while he associated the rational with the transcendent and the divine. The irrational was casting its shadow on the archetypical perfection which resulted in the existence of evil in the world.

Already prior to Socrates the Greek philospher Heraclitus introduced the term Logos. Universal Logos represented a divine ordering principle behind all things and events. Heraclitus saw most people as sleepwalkers in a false dream, because they did not understand the principle of Logos and thus lived in disharmony with the world. Plato picked up on this aspect and integrated it into his philosphy of an understandable world.

Aristotle

The philosopher Aristotle grew up under the influence of Plato's world view but eventually he developed his own completely independant philosophy. Aristotle opposed the idea that the true reality could only be found on a transcendental level. As an alternative model he developed his teaching of categories : Within the ten categories he defined, "substance" was primary and defined what all objects are made of. Other categories like quality, quantity or relation were derived attributes, which only became meaningful when assigned to an object with substance. For Aristotle the world consisted of individual, separated substances, which shared certain attributes with other substances. By replacing Plato's concept of transcendantal ideas with universal categories - attributes which the mind could grasp with the five senses - he turned Plato's principles of a divine order upside down.

Aristotle's approach, that understanding of the natural world could be attained by perceiving the world with the five senses, was more appealing to people than the abstract approach of Plato. Additionally Aristotle introduced earlier concepts of astronomy into his philosophy : The world was the center of the universe and all celestial bodies were circling around it. He differentiated between the 5 known planets at that time and the starry sky as the background. For the 5 planets, the sun and the moon a model of concentric spherical shells that circled the Earth was developed.

Aristotle's heritage consisted mainly of logic, empiricism and natural science. While during the Ancient World Plato was considered the most important philosopher of his time, the view of history changed during the Late Middle Ages : The philosophy of Aristotle turned out to be trend-setting for scientic research of the West until the 17th century.