* Economic motivations: Spain was facing severe economic difficulties in the late 15th century. Gold and silver were highly valuable commodities that could bolster the Spanish treasury and fund further exploration and expansion.
* Religious zeal: The Spanish saw their voyages as a way to spread Christianity and convert indigenous populations to Catholicism. They believed they were fulfilling a divine mission to spread the faith and civilization.
* Political ambitions: Spain was competing with other European powers, such as Portugal, for control of trade routes and resources. The discovery of gold and silver in the Americas would give Spain a significant advantage in this competition.
While the Spanish were also interested in finding other resources, like spices and new trade routes, the search for precious metals was their primary goal. This led to the exploitation of indigenous populations, the establishment of vast colonial empires, and the creation of the infamous "silver drain" that ultimately contributed to the decline of the Spanish Empire.