Thunder (☳) — Arousing

One yang line beneath two yin — force erupting upward, the shock that initiates movement. Thunder is the eldest son, the arousing principle, the first spring thunder that breaks winter's stillness. It appears in fifteen hexagrams, carrying qualities of initiative, shock, and the energy that sets things in motion. Its associated season is spring; its direction is east; its nature is movement that cannot be stopped once it begins.