The only lecture,[575] of which any very definite trace is left, was not a great success from the educational point of view. Plato announced beforehand that his subject would be “The Good.” A great crowd collected, expecting to hear a neat Isocratean discussion of such things as Health, Wealth, Friendship, which were popularly considered to be rival claimants for the title of the Good. But Plato began to talk about arithmetic and geometry and astronomy, and discussed the One as the Good. The whole lecture was couched in enigmatical language. The majority of the audience went away in despair.[576] Only practised Platonists like Aristotle and Herakleides and Hestiaios did their best to understand the lecture, and took notes. The whole idea of a “popular lecture” must have been repugnant to Plato. In his view, knowledge was only for the few, who, starting with great natural abilities, could devote themselves for years at a time to continual study and research. The pupil must be talented to start with: he must undergo a long course of preparatory studies in Logic and Mathematics: only when middle-aged might he approach the inner mysteries of Philosophy. Holding such educational ideas as these, Plato naturally made his lectures unintelligible to all but a few: his main subject for public exposition seems to have been that curious mathematical metaphysic which Aristotle combats as Platonic, although it is nowhere found in the extant dialogues. By reading the _Metaphysics_ of Aristotle the modern inquirer can perhaps realise how difficult Plato’s lectures must have been.[577] At the school in the Akademeia, Plato seems to have instructed his lads chiefly in Logic and Mathematics. Logic consisted chiefly of definitions, such as those for which Sokrates was always hunting, and that curious process of “division” which is exemplified at such length in the _Sophist_ and _Politikos_. Diogenes Laertius[578] gives a long catalogue of such divisions, of which only a few can be found in extant works: the rest must have figured in the school, and survived as traditions in the commentaries. A comic poet has left a picture of the logic school at work[579]:―― “_A._ What of Plato and Speusippos and Menedemos? Upon what are they now engaged? What is their thought? What argument is investigated among them? Tell me, I pray, if you know.