On Aristotle's Metaphysics, book 4 (aka Gamma) (ca. 340 BCE). What does studying "being" entail? It involves claiming that all beings are distinct individuals, as opposed to, for instance, an undifferentiated flux. They're thus subject to the law of non-contradiction, which Aristotle defends against objectors. Get more at partiallyexaminedlife.com. Visit partiallyexaminedlife.com/support to get ad-free episodes and tons of bonus discussion. Sponsor: Get 50% off delicious, ready-to-eat meals at FactorMeals.com/pel50 (code pel50).