The British generally saw the colonies as a source of revenue. The idea of mercantilism, the economic theory that guided the colonial relationship, was that, by maintaining a favorable balance of trade with the colonies, the British Empire would profit. Essentially, the colonies functioned as suppliers of raw materials, including cash crops like sugar and tobacco, and consumers of British manufactured goods, ranging from cloth to glass to guns to paint. The colonies also supplied large quantities of naval stores, including tar, pitch, and timber for the construction of ships. In order to maintain this profitable relationship, the British Crown and Parliament established a series of regulations that prohibited the importation of non-British goods into the colonies. These restrictions, however, were seldom enforced with any regularity, a policy called "salutary neglect" after the fact. As long as the colonies remained profitable, it was not in the British interest to spend much in enforcing them. When they began to do so, beginning with the Sugar Act in the wake of the French and Indian War, the colonists protested.