An apple of iscord is a reference to the Golden Apple of Discord which, according to Greek mythology, the goddess Eris (Gr. Ερις, "Strife") said would go "to the fairest" at the wedding of Peleus and Thetis, sparking a vanity-fueled dispute between Hera, Athena and Aphrodite that eventually led to the Trojan War (for the complete story, see The Judgement of Paris). Thus, "apple of discord" became a euphemism for the core, kernel, or crux of an argument, or for a small matter that could lead to a bigger dispute.