Elle Macpherson confessed she "just liked the sound of it", thus avoiding to make a fool of herself with Biblical explanations (see the post about Claudia Schiffer below). I don't like the sound of it at all, but then I don't know how it sounds in Australian English.

There is only one Aurelius, and before Elle not many thought of using his name: Marcus Aurelius (b. April 26, AD 121, Rome--d. March 17, 180, Vindobona [Vienna], or Sirmium, Pannonia), Roman emperor (AD 161-180), best known for his Meditations on Stoic philosophy. According to the Columbia Encyclopedia, Marcus Aurelius has symbolized for many generations in the West the Golden Age of the Roman Empire.

But he is also an initiator of Christian persecution. Still, though Aurelius disliked the Christians, there was no systematic persecution of them during his reign. Their legal status remained as it had been under Trajan and Hadrian: Christians were ipso facto punishable but not to be sought out. This incongruous position did little harm in times of general security and prosperity, but when either of these were threatened, the local population might denounce Christians, a governor might be forced to act, and the law, as the central authority saw it, must then run its course. The martyrdoms at Lyon in 177 were of this nature, and, it appears that Christian blood flowed more profusely in the reign of Aurelius the philosopher than it had before. (take that, Caspar!)

The Britannica Encyclopedia is far less generous for Elle Macpherson's inspiration source:
"Aurelius was a statesman, perhaps, but one of no great calibre; nor was he really a sage. In general, he is a historically overrated figure, presiding in a bewildered way over an empire beneath the gilt of which there already lay many a decaying patch. But his personal nobility and dedication survive the most remorseless scrutiny; he counted the cost obsessively, but he did not shrink from paying it".

And it seems from the engraving works that he wouldn't look good in a bikini, either.