In this 1787 pamphlet, Cooper describes the abolition of the slave trade as a national duty: "if we claim Freedom as our birth-right, and glory that the 'very air of our country is too free for a slave to respire'; we are in honour bound to assist in exterminating the most diabolical exertion of political tyranny..." (4). His letters provide an overview of the slave trade, citing early abolitionist writings and eye witness accounts from the work of Benezet, Woolman, Sharp, Wesley, Clarkson, Abbé Raynal etc., as well as the slave ship Zong trial of 1783.