A few hundred years from around 800 to 200 BCE witnessed a major re-evaluation of the Bronze Age legacy across human civilisation. Four great cultural centres in particular laid spiritual and philosophical foundations that have profoundly influenced human society to the present day: ancient Israel, classical Greece, Buddhist India and Confucian China.
Greece produced the poetry of Homer, the philosophy of Heraclitus, Pythagoras, Socrates and Aristotle; Platonism would become a major influence on Western thought, including Christianity, for centuries.
In India, a prodigious blooming of intellectual and spiritual life produced philosophers including atheists and materialists among their number; the 6th–5th century BCE (the dates are disputed) brought us the teachings of the Buddha; in the 6th century BCE Jainism was founded; Hindu philosophy produced the Upanishads and in the 5th–2nd century BCE the Bhagavad Gita as part of the epic Mahabharata.
In China, Confucius (551–479 BCE) and his followers produced the Analects, and the founder of Taoism, Lao Tzu (traditionally 6th century BCE), produced the Tao Te Ching (or Daodejing). These have been the most widely read and studied texts in China.
In Palestine, the great Hebrew prophets – Elijah, Isaiah, Jeremiah, Deutero-Isaiah – laid the foundations of the Abrahamic religions, producing the canonical texts of the Hebrew scriptures.
And we should add that in Persia, possibly around the 7th–6th centuries BCE, Zoroaster (or Zarathustra) founded a philosophy and monotheistic religion that survives to this day.
These currents of thought, giving us the first real classics of literature, seem to have arisen more or less independently, all of them asking very modern questions about the nature of reality and humanity’s place in it. It is striking that so many seminal figures were alive at the same time and many could even have met each other. Clearly, humanity in this period was bringing traditional practices and beliefs into question and speculating with great creativity about how to conceive and change the world. The German philosopher Karl Jaspers described this as the Axis or Axial Age: “the point most overwhelmingly fruitful in fashioning humanity”  – the axis or hinge upon which world history turned.
Merlin Donald on theoretic culture
Over a space of few centuries humanity experienced a leap to a new level of intellectual sophistication. So what was happening here?
An insight into this phase of human civilisation was proposed by the Canadian psychologist and cognitive neuroscientist Merlin Donald in his book Origins of the Modern Mind. Donald argued that human cognition had passed through three broad stages. Early humans made a transition from the ‘episodic’ cognition of animals to a ‘mimetic’ stage, characteristic of Homo erectus, which features gesture and non-verbal communication. The next transition, concluding with our species, Homo sapiens, was the ‘mythic’, which featured language and narrative thought. The final stage was the ‘theoretic’, representing the emergence of institutionalised, theoretical thought. This development depended upon the expansive use of external memory storage, which in most cases requires writing. Instead of relying upon oral culture and upon human biological memory, human culture invented written archives, as well as the other existing ways of recording our ideas such as monuments and works of art.
Put into Donald’s terms, the Axis Age was the period of human history in which mimetic and mythic culture was joined by the theoretic. This was a cultural rather than a biological change, and it was profound. Literacy had been invented much earlier, but only now did humanity develop a truly literate culture. To put it simply, we shifted from oral tradition to libraries. External memory storage changed the way humans approached reality and its attendant puzzles such as religion, perception and society. Taking the Greeks as his example, Donald writes:
Our concern here is not so much with the history of science or philosophy per se as with the cognitive framework that enabled such accelerated change. How had the structure of human thought process changed? The answer appears to be at least partly that, in the ancient Greeks, all of the essential symbolic inventions were in place for the first time. The evolution of writing was complete; the Greeks had the first truly effective phonetic system of writing, so successful that it has not really been improved since. They also possessed advanced systems of numeration and geometric graphing. Astronomy had advanced considerably under the Babylonians, and the Greeks were aware of that body of knowledge, as they were of Egyptian mathematics. Moreover, their society was open, intensely competitive, and sufficiently wealthy that education went beyond the immediately pragmatic.
The key discovery that the Greeks made seems to have been a combinatorial strategy… In effect, the Greeks were the first to fully exploit the new cognitive architecture that had been made possible by visual symbolism.
For the Phoenicians, writing was mostly a mercantile tool; in Greece, every educated male could read or write. The Greeks externalised their speculation upon reality through the widespread use of literature, which stored ideas in a more reliable and permanent form than was possible under the oral tradition. Written opinions on the natural world, law, sculpture, etc could be placed into the public domain to be analysed, discussed and improved upon, even after their originators had died. The Greeks “founded the process of externally coded cognitive exchange and discovery” (Donald), using external memory storage to create a collective social memory. Greek culture stepped out of the oral tradition dominant during Homer’s time and began the journey that culminated in the Library of Alexandria.
Although, because of a particular combination of elements, this process was perhaps most intense in Greece (their 5th century BCE heyday pivoting in the very centre of the Axis Age), it produced a systematic inquiry into the nature of things in four major centres of world culture. It did not spring up fully formed, it was uneven, and it drew heavily upon earlier innovations; nonetheless the Axis Age was not a historical coincidence but a fundamental cultural shift. This shift to libraries was much more significant than the modern age’s great ‘information’ innovation, namely the internet.
It is true that classical Greece produced some of the greatest achievements of the ancient world. But anyone who wishes to claim it as the single, direct ancestor of the West, or as a brilliant moment of uniquely European enlightenment, is required to ignore great swathes of historical context. He or she must become, as Edward Said put it:
someone who wants to make ‘civilisations’ and ‘identities’ into what they are not: shut-down, sealed-off entities that have been purged of the myriad currents and countercurrents that animate human history.
 Karl Jaspers, The Origin and Goal of History (1949).
 Merlin Donald, Origins of the Modern Mind (1991).
 Edward Said, ‘The Clash of Ignorance’ (in The Nation, 2001). Said is commenting here on Huntington’s The Clash of Civilisations, but the principle applies.