The Renaissance
In the Middle Ages the most important value was religion because people were afraid of life after death. People lives were based on achievement of salvation and heaven. It followed that religion played a role of supremacy in political, social and economic field. There was a hierarchical society where the Pope was on the top.
During the Middle Ages, an open conflict between religious/temporal power and temporal power of the Empire broke out. Temporal power was growing steadily and active life and all that men could do started to be considered more important.
Now people change their point of view and their priority: life on Earth was taken into much more consideration then life after that.
There was a period where both the Chain of Being and the new conception of God coexisted and people tried to find an answer to the question connected to the human being sense of life in the Classical literature of Greece. This transition period between the Middle ages and Renaissance was called Humanism.