Of the " Nobody " Argument, addressed to Epicrates, one book. Ninth series : Of Sophisms, addressed to Heraelides and Pollis, two books. Of Dialectical Puzzles, addressed to Dioscurides, five books. Reply to the Method of Arcesilaus, dedicated to Sphaerus, one book. Tenth series : Attack upon Common Sense, addressed to Metrodorus, six books. Defence of Common Sense, addressed to Gorgippides, seven books. V. Under Logic. Thirty-nine investigations outside the range of the four above-mentioned main divisions dealing with isolated logical investigations not included in separate wholes of the subjects enumerated. The total of the logical writings is three hundred and eleven. 1. Ethics dealing with the classification of ethical conceptions. First series : Outline of Ethical Theory, addressed to Theoporos, one book. Ethical Theses, one book. Probable Premisses for Ethical Doctrines, addressed to Philomathes, three books. Definitions of the Good or Virtuous, addressed to Metmdorus, two books. Definitions of the Bad or Vicious, addressed to Metrodorus, two books.