Apple of Discord

An apple of discord is a reference to the Golden Apple of Discord, which, according to Greek mythology, the goddess Eris said that she would give "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. 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. 

The Apple of Discord has 19th century B.C. origins involving the Hattian and Gnostic lore. The Apple of Discord represents humanity's inability to understand the world above the necessity of self-preservation.