Final answer:
The poem 'Ozymandias' primarily conveys the theme that 'art can endure,' even as empires fall and nature erases human achievements. It reflects the Platonic ideal of eternal beauty captured through art.
Step-by-step explanation:
The poem 'Ozymandias' by Percy Bysshe Shelley relates the discovery of an ancient statue in the desert and conveys themes of the impermanence of power and the enduring nature of art. The correct additional theme that the poem conveys is art can endure. The 'shattered visage' of the statue still communicates the king's commanding personality and the sculptor's skill, long after the empire itself has crumbled. This is in line with Platonic thought, which values the eternal forms of truth and beauty over the transient physical world. Thus, despite the poem showing that human achievements and even beauty can be eroded by time, the enduring art captures the essence of both the subject, Ozymandias, and the sculptor's interpretation of beauty.