Final answer:
The main purpose of colonies, according to mercantilist theory, was to enrich the mother country through a favorable balance of trade.
Step-by-step explanation:
According to mercantilist theory, the main purpose of colonies was to enrich the mother country through a favorable balance of trade. European nations established colonies to secure a steady supply of raw materials for domestic consumption and to create a market for goods produced in the home country. These colonies were usually required to trade exclusively with the mother country, ensuring economic benefits for the colonizing nation.