What were the causes of the Italian Renaissance ?

The Crusades was an important cause of the Italian
Renaissance.  The Crusades helped end feudalism in Western Europe and brought about the
conditions that helped create the Renaissance.  The Crusades began the breakdown of
feudal society in Western Europe.  Many feudal lords went off to fight and die in the
crusades, leaving their serfs free to go to towns and start new lives.  Monarchs gained
new strength when knights left to fight in the crusades in the Middle East.  This
increase in the power of the monarch also helped to end feudalism.  Crusaders brought
back goods such as spices and cloths, which increased demand for these goods. 
Merchants, particularly in Italy, grew rich from this new trade with the East. 
Crusaders also brought back Greek and Roman classical works.  The wealth from trade and
new knowledge of classical Greek and Roman works sparked the Renaissance in
Europe.