Poet Percy Bysshe Shelley felt inspired to write the poem "Ozymandias" due to archeological discoveries being made in Egypt as a result of Napoleon's defeat of Egypt in 1798, nearly 20 years before Shelley wrote the poem. One evening in 1817, Shelley recalled Roman historian Diodorus Siculus's description of a statue of Ozymandias with an inscription (Poem Guide, "Percy Bysshe Shelley: "Ozymandias" A Poem to Outlast Empires"). Ozymandias is also known as Ramses II, an Egyptian pharaoh famous as a warrior for reconquering land that had been previously lost to the Egyptian Empire in older battles (Encyclopaedia Britannica, "Ramses II"). Historian Siculus described the inscription on Ramses II's statue as having read, "King of Kings Ozymandias am I. If any want to know how great I am and where I lie, let him outdo me in my work" (Poem Guide). However, neither the statue nor the inscription described by Siculus have survived. Regardless, it is Siculus's description that served as Shelley's inspiration for a poem about past days of glory that now exist only in a state of decay. Since the poem reflects on Ozymandias's old days of glory that our now decayed and forgotten, we can easily see how the poem also reflects change.
The theme of forgotten days of glory is especially captured in Shelley's own made-up version of the inscription Siculus described. Shelley's own version is seen in the last four lines:
Look on my Works, ye Mighty, and despair!
Nothing beside remains. Round the decay
Of that colossal Wreck, boundless and bare
The lone and level sands stretch far away!
In these lines, Shelley is quoting the inscription as saying that even the greatest works, such as the "mighty" works of Ramses II are worth nothing more than "despair" because, as time marches on, nothing remains of those works. All that can be seen of those works is "sands stretch far away." Since time has destroyed the evidence of Ozymandias's, or Ramses II's, brave works as a warrior, we can easily see how the poem reflects the theme of change over time, or even more specifically, the theme of destruction over time.