This lecture discusses the ancient Greek philosopher Aristotle' work, On Interpretation, focusing on his discussion near the end of the work bearing on what the contraries of affirmative, generally universal, proposition, actually are, since this is an issue that people often get confused over. Aristotle will resolve this partly by considering in propositions what is the case by essence (kath'heato), or accidentally (kata sumbebēkos).To support my ongoing work, go to my Patreon site - www.patreon.com/sadlerIf you'd like to make a direct contribution, you can do so here - www.paypal.me/ReasonIOYou can find over 4,000 philosophy videos in my main YouTube channel - www.youtube.com/user/gbisadlerPurchase Aristotle's On Interpretation - amzn.to/3nS55ud