_Symposium_, an exposition of his entire doctrine in “love speeches.” It is the most artistic of his writings, and represents the climax of his intellectual power (385 or 384 B. C.). _Republic_ (major portion). The composition of the _Republic_ extended over a long period. It is a discussion: (1) concerning justice (written in the second period, see above); (2) concerning the ideal state which shall realize justice; (3) concerning the Idea of the Good and in criticism of the constitutions of states. It is Plato’s masterpiece and his life work. _Parmenides_ and _Sophist_, written to express the objections to the theory of Ideas, and to discuss such objections. (Windelband holds these dialogues were not written by Plato, but by some member of his school. This is, however, not the consensus of opinion.) _Politicus_, a discussion of the field of knowledge and of action for a statesman. _Phædo_, Plato’s final will and testament to the school, written shortly before his third Sicilian journey, in 361 B. C. It is his completed conception of the Idea of the Good and of the relation of other Ideas to it. It contains Anaxagorean and Pythagorean elements. _Philebus_, concerning the ingredients of the Idea of the Good. _Timæus_, Plato’s conception of physical nature, expressed in mythical form. _Laws_, the work of Plato’s old age, his revision of the ideal State. =Concerning the Dialogues[28] of Plato.= The early philosophers presented their philosophy in metrical form as poems “concerning nature”; Socrates perpetuated his teachings through conversations with men; Plato made his influence permanent by written dialogues; Aristotle’s philosophy, in the works that have been preserved, stands in the form of treatises whose sole purpose is that of exposition. Plato’s dialogues therefore have a twofold place in the history of literature. On the one hand, in the history of literature proper we have already mentioned them as standing after the Greek drama in the development of Greek dialectics; on the other hand, in the development of philosophical instruction they stand between the conversations of Socrates and the scientific expositions of Aristotle.