'Exert' means to apply force on influence over something else, this can be in a negative or positive way. In this quotation, it means that language, if used correctly, has the ability to express a 'hidden power'. It's also worth mentioning that the simile is relevant as the moon has an influence on the level of tides on Earth.
The triangle trade, also called Western or Atlantic slave trafficking, was a slave trade conducted between Europe, Africa and the Americas between the XVIe and XIX centuries. Its aim was to provide black slaves to colonies of the New World (America), to supply Europe with products from these settlements and to sell in Africa,European and American products. This was, for the European ships, to bring to the Atlantic coasts of Africa different goods of European origin, objects of little value, guns, weapons... highly appreciated by Africans. Goods were exchanged for black African prisoners, who were then forced to go to Americas. Here men, women, children... were sold as slaves to work in the cotton or sugar cane fields.The ships then returned to Europe with American coffee, sugar, cotton, rum which were resold. This trade lasted from the XVIe century until the early XIXe century. They say it was triangular because, on a map, it was represented by arrows connecting Europe, Africa and America which draw a triangle.
The answer is a it has nothing to do with violence
because it taught and showed him what to keep in mind