Speaking of Greeks, they believed that such universal ideas come from the world of ideas, or the world of archetypes; great thinkers merely perceive this world,

Speaking of Greeks, they believed that such universal ideas come from the world of ideas, or the world of archetypes; great thinkers merely perceive this world, and that's why different cultures seemingly by accident end up with the same ideas in their "books of wisdom". In this worldview, the achievement of greek or indian philosophers isn't creating the idea of the four ages, but expressing it in the limited thoughts framework they had to deal with. It's a lot like how painters try to express what they see on a small flat rectangle of paper.