In ancient Greece, the slave system allowed the production of intellectuals, who had time and wealth to dedicate their activity to knowledge, to science.
During the Renaissance, in Europe and particurly in Italy, the “return” to this knowledge of Ancient Greece was formulated as the way to leave the Middle Ages behind.
In fact, the philosophical ideology of ancient Greece was taken up by the growing bourgeoisie and used as a tool to weaken religion, in a defensive way in Italy and France, whereas elsewhere Hussitism and Protestantism became militant ideological forms of political Averroism, through open struggle with feudalism.
Therefore, the “myth” of ancient Greece as the main “source” of knowledge was much stronger in Italy and France than in countries that would later become Protestant.
The thought of the Renaissance was based on neo-Platonic mysticism, as exemplified by the Italian Marsilio Ficino (1433-1499), and took the form of a mystical compromise with Catholicism; as for Protestant thought, it was already a complete bourgeois thought system in the field of ethics, all geared up towards promoting the ideology of capitalism.
On one side there is a fascination for the Renaissance paintings of fat little angels, on the other side there is admiration the realism of Flemish painting.
If we take a closer look, we can see that what happened in ancient Greece also happened in ancient India. There was a civilization based on slaves too, and we can find a whole history of intellectuals developing knowledge and science as well.
Of course, the issues were different because of distinctive economical and cultural situations. In ancient Greece, it was the question of space that was the most important, which means that the concept of movement was central.
Was the universe always the same or moving? How did the planets move? How did the species reproduce themselves, what kind of movement was it? Were there atoms, or was matter formed by “forms” produced by a motor as a source of movement? Was this motor in movement or not? Was our reality in movement, reproducing a static world of ideas?
In ancient India, it was not the question of space that mattered, but the question of time. The direction was totally different. And as in ancient Greece, it produced numerous battles opposing the idealist trend to the materialist trend.
Moreover, the class struggles induced ideological revolutions. Brahmanism collapsed in the face of class struggle and had to change into Hinduism. There were even bourgeois trends, that produced Buddhism and Jainism, but the bourgeois Buddhism was crushed in ancient India, and Jainism maintained itself as a form of compromise and in submission to Hinduism.
Then, the Islamic invasions modified Hinduism again, which had to take various forms to maintain itself, and then British colonialism changed the situation again, giving birth to the Hinduist ideology we know today.
The importance of this question must be emphasized. More than a billion people are concerned by these ideologies of Hinduism, Buddhism and Jainism. If we take into account the Islamic culture of countries in direct relation to India, we have to add hundreds of millions of people; it we consider the Asian countries that salvaged Buddhism and developed it accordingly to their situation (Sri Lanka, China, etc.), we then have to add more than a billion people.
But this is not all. Hinduism, Buddhism and Jainism have all addressed an issue of central importance: the question of the conscience.
These religions negated the ego, the “self”, which means that they understood already that the human doesn't think, that he is only an element of an eternal matter in movement. Nervermind if the answers were rarely materialist, but mostly idealistic and ultimately reactionary, raising this issue was in itself a great contribution to knowledge and science.