Beneath the thin crust of continents and oceans lies the mantle — a vast layer that makes up roughly 84% of Earth’s volume and nearly two-thirds of its mass. The upper mantle is composed primarily of peridotite, a dense, olivine-rich rock. The mantle is massive and opaque. Everything on Earth's surface — mountains, cities, oceans — rests on this dark, unseen mass. Philosophical parallel: A strong core, even when it goes unnoticed, keeps one grounded. The structure and integrity of one's soul will outlast one's short-term reputation and illusions.