Final answer:
The best summation of the theme of 'Ozymandias' is the impermanence of power and the ephemeral nature of human achievements.
Step-by-step explanation:
The central theme of Percy Bysshe Shelley's poem Ozymandias revolves around the transient nature of power and the inevitable decay of all things. The poem describes the ruins of a once-mighty statue of the pharaoh Ozymandias, which serves as a profound commentary on the ephemeral nature of human achievements and the hubris of rulers who believe their legacies will endure forever. Through powerful imagery, the poem suggests that no matter how great one's power might be, time and nature will eventually erode all physical manifestations of that power, leaving nothing but a memory, which itself may fade.