One great art in argument when you have the first move is to divide everything into that which is and that which is not in some assigned class. In this way you make it the business of the opponent to discover what other important things there may be which may be said of the subject in hand.
Quoted in Lewis Campbell and William Garnett, The Life of James Clerk Maxwell: With a Selection from His Correspondence and Occasional Writings, Chapter VIII (p. 233)