- Classical Learning: The rediscovery and study of classical Greek and Roman texts, art, and architecture inspired the Renaissance's focus on humanism and the reemergence of classical ideals and aesthetics.
- Humanism: A philosophical movement that emphasized the value of human reason, individuality, and achievement, shifted focus away from the theological dominance of the Middle Ages.
- Trade and Commerce: The growth of trade and commerce, particularly in Italian city-states like Florence and Venice, created wealth and patronage that supported the arts, literature, and scholarship.
- Printing Press: The invention and spread of the printing press in the mid-15th century facilitated the dissemination of ideas and knowledge across Europe.
- Urbanization: As cities began to grow during this period, people became exposed to new ideas, innovations, and opportunities.
The crusades, on the other hand, were religious military expeditions launched by European Christians to recover the Holy Land from Muslim control. These occurred primarily during the 11th-13th centuries and had various political, economic, and religious motivations but not directly related to the Renaissance's intellectual and cultural changes.
The population decline in the 14th-15th centuries was primarily caused by the Black Death, a devastating pandemic that killed millions across Europe. This calamity did have some societal and economic effects, but it was not the sole instigator of the Renaissance.