Despite the incredible flowering of the Sumerian, Egyptian, Persian, and Indus Valley civilizations during the 7500-3500 Before Christ period, the influence and permanence related to the Greek Civilization is still unparalleled in the ancient and present eras. It seems a very simple question as to what could be the one vital reason for the enduring marvel of that age. But, there can be multiple answers to this apparently uncomplicated query. Depends upon the sensibilities of the times we live in.
I, for one, would say that the Greek Revolution was a product of intellectual endeavours on the unconscious levels, at first. Meaning it wored basically on the intuition with regards to the Positive Forces in the universe. Later, as the intellectuals of the Greek nation were driven to reach out to a knowledgeable strata of the society, they attracted students and pupils, and opened schools and academies. Like, for instance, the schools of Pythagoras and Aristotle. It is true that the Greek philosophers did not directly communicate with the common folks, and to some extent, they shunned the common worker from their society, but their intellectual influence reached out to the society through other means. Like the dramatists, stand-in artistes, street thinkers, etc. who were influenced by them. The wisdom in the streets was imparted by people like Socrates, who was considered by the Oracle at Delphi as one of the wisest men of Greece. The processes that led to democracy, and also the general questioning of the gods of Olympus, were all the results of the influence of these intellectuals. That was the reason that a leader and conqueror like Alexander was born, who really believed in the equality of people, despite his thoughts on a Global Government, having been taught under the tutelage of Aristotle.
Over all, it was a social revolution in Greece, at first, which triggered a political revolution, later. But, that isn't necessarily always the case in revolutions. Sometimes political awareness triggers a social revolution, like it happened in the French Revolution, or it could be a workers' or peasants' understanding of their rights that gradually transforms into a social revolution, as happened in the case of the Russian and Chinese Revolutions, which are termed Socialist and Communist Revolutions, respectively.

One must understand the scalars and vectors of history before one can change, or strive to change a society. The chaos we see in this country, Pakistan, today, is that we have no workable knowledge of these scalars and vectors of the history. When I talk about the Greek Revolution, I am talking about the Positive Forces. The positive thinking of intellectuals, artistes, and the scientists of a nation. The Greek nation benefited from this kind of intuitional stuff, which was like a light source, distributing shafts of light to different sections of the society. That is why every section of Greek society developed a culture of intellectual growth. Reason became the prime issue. Aristotle preached the growth of character in the institutions before these individuals would take on the responsibilities in the society, a thought that is the crux of institution of Khilafat, later, in the Islamic Revolution in Arabia. Socrates questioned the gods, and sacrificed his life for the cause, saying that he could not hide the truth. Thus, it was inevitable that Socrates would be followed by Jesus (PBUH), in 4 BC, who ascended on the wings of a total sense of liberty.
It's all about the Positive Forces.
But, strictly speaking in terms of the historic scalars and vectors, the Greek Civilization flourished on the visionaries. Socrates proves in Plato's book, Dialogues that he believes in a mystical oneness, which conveys messages to him. His idea of the Republic is also something based on values, though selective ones, and this also influenced the democratic rule later on. If you want to know how this Positive Force worked for the Greeks, you can read the passages, in Herodotus' Histories, which concern the incredible military struggle that ensued between the proud Persian King, Xerxes, and the Greek army. You can watch the same struggle between the Positive and the Negative forces, in this context, in the new historical film, 300, which is based on the same struggle between the Persians and the Greeks. Herodotus mentions in his book that the Persians, though believers in kingship, tried to thrash out the issue of democratic rule, before Darius finally waived off any such experiment aggressively, in a long speech, and took over as the next king of Persia. When Herodotus moves on in his Histories, he relates that the Persians under Xerxes were a massive army, and Xerxes had been told in a dream, one night, in no uncertain terms that he must invade Greece, or he would find life terrible in the coming months. When you read that passage, you will know that that was no Positive Force, which wanted Xerxes to follow such an interventionist policy, but a Negative Force that wanted to extinguish the Positive Light burning in Greece.
After the Greek Civilization, the Roman Civilization took over, and it was a totally different scheme of things. The Romans, despite some positive aspects, believed in a world empire, which would have the Roman Emperor as the centerpiece of the Earth, much like the Persians. As against the visionaries of Greece, the Romans were primarily expansionists, with no equality of the races at heart. Their intellectuals were not behind this Roman Hierarchy of Nations, but some of them had to back the dictators in order to be in a position of prominence, like the philosopher Seneca, who did not dissuade Nero from burning the locality of the Christians that has become proverbial in our languages. Poets like Ovid, who wrote Metamorphosis, wrote about legend and myth, which is very revealing indeed, but, they hardly lingered on progressive thoughts like democratic norms and reason-based issues. That was the reason that Julius Caesar shunned the Roman Parliament to lobby for Roman Dictatorship. This, finally, caused some parliamentarians like Brutus to plan the assassination of Julius Caesar, and accomplished it soon. Still, dictatorship prevailed, and a bad precedent was set, which shows you that it was the Negative Force that took hold of the Roman Empire.
Actually, Rome was beset by evil dictators like Nero, Caligula and others. Although they came after the Ascension of Jesus, they were the ones that made Rome a place of great malice, cruelty and dark evil. They were literal psychopaths, and their vision was clouded by apple-polishers and hangers-on, who made a most disgusting retinue in the royal court. But, to worsen the situation, both Nero and Caligula were freaks, and were not only politically corrupt, but also psychologically stressed out. Nero not only encouraged the blood bath in the stadia, where gladiators fought against men and beasts, but added another novelty to it! He started the trend of bringing the rebels and detractors of the government to the stadia, and hanged them, or threw them in front of the beasts. When the Christians became a 'political nuisance,' for them, denouncing their stony idols, and generally pointing fingers at the system of governance, Nero put them on the specially erected crosses in the Coliseum, and killed them with extreme cruelty. And, of course, the burning of Rome I have already mentioned, though today, the theory is being forwarded that be may Nero wasn't responsible for the fire after all! Whatever the analysis from archaeological finds, the fact is that Nero did abhor the new religion, and dealt with the Christians with great cruelty. But, at the same time, just before the coming of Nero and Caligula, another Positive Wave, in the shape of Christianity, had already taken over in Judea. The Dark Powers invested in Rome were to be faced by a Tower of Light, Jesus (Hazrat Essa AS). This was to be an ideology of an imperialist empire against an ultimate man of peace. The leering evil of imperialist Rome was to be tested by this Positive Shaft.
But, would a massively developing imperialist empire even notice the holy prophet?
But this we will discuss next week in detail.