This is a very interesting question ! If what you mean by Classical Platonism is the system , based on Plato ' s writings and oral teachings , discussed in antiquity , then probably , the chief text is the Timaeus the Theaetetus would definitely be up there , too . The Republic , in contrast , would have not been nearly so important . The Phaedo was very important , same as it is today . Every Platonist would have read the First Alcibiades , which few people have read today , even though it is wonderful . However , if you want some list of essential readings that you should do to understand Plato ' s thought , I would really recommend the Republic more than the Timaeus or Theaetetus , as good as they and especially the latter are . For more information about Classical Platonism in the ancient sense , you can check out Lloyd Gerson ' s From Plato to Platonismtel 9160 faauthorpersonid 3716 and Charles Brittain ' s Plato and Platonism . Both are great . As for Aristotle , his Metaphysics especially book twelve , also called Book Lambda was super important in the ancient world and still great today still , you should probably start with the Nicomachean Ethics and Politics . My personal favourite is the Posterior Analytics , a work very broadly concerned with epistemology and logic . His De Anima and Physics are two other works that mattered a lot in antiquity and still matter today .