And it is further enacted by the authority aforesaid, that no goods or commodities (no sugars, tobacco, cotton-wool, indigoes, ginger, fustic, or other dyeing wood, of the growth, production, or manufacture of any English plantations in America, Asia, or Africa, shall be shipped, carried, conveyed, or transported from any of the said English plantations to any land, island, territory, dominion, port, or place whatsoever, other than to such other English plantations as do belong to his Majesty)… ...whatsoever, of the growth, production or manufacture of Africa, Asia, or America, or of any part thereof, be imported into England...in any other ship or ships, vessel or vessels whatsoever, but in such as do truly and without fraud belong only to the people of England...or of the lands, islands, plantations or territories in Asia, Africa, or America, to his Majesty belonging, as the proprietors and right owners thereof, and whereof the master, and three fourths at least of the mariners are English; (2) under the penalty of the forfeiture of all such goods and commodities, and of the ship or vessel in which they were imported, with all her guns, tackle, furniture, ammunition, and apparel;

The Navigation Act of 1660

1) What is the main idea of the above law?