""The Substance of a Letter: Addressed to a Clergyman of the Established Church, on the Subject of War"" is a book written by John Clarkson and published in 1827. The book is a letter written by Clarkson to a clergyman of the Church of England, in which he argues against the morality and necessity of war. Clarkson presents a pacifist perspective, arguing that war is not only morally wrong, but also counterproductive and harmful to society. He critiques...