Right, right. But they had a powerful, oppressive force: the Church. They would also burn you as soon as you affirm planetary motion doesn't come from god, that earth is not the center of the universe, or anything that slightly contradicts their vision of the world. But not before torturing you until you accept everything you said was a lie... As you can see, there was a lot of innovation going on, Europe was totally a fertile ground for scientific discovery :^)

Philosophy changed that, and you might want to take a look at where that philosophy came from, who translated it and when.

But you have to consider that those are the same philosophies wide adopted from the church itself.

In that Age there was so many processes in the name of Plato or Aristoteles...

Saint Thomas Aquinas is credited as being one of the most influential scholastic philosophers of that time. He studied under Saint Albertus Magnus, that based his work mostly on annotated Latin translations of Aristotle obtained from Toledo.

But It is not a kind of phylosophy the Key of the modern age, but It is the possibility to reject any dotrine.

Except that religion was very hard to oppose since the foundation of religion are the dogmas of faith.