Aeschlyus was the earliest ancient Greek playwright whose plays survive today. His trilogy, The Oresteia, is seen by many critics as a key work establishing many of the dramatic conventions that characterise our ideas of ancient greek tragedy.
Prometheus Bound was Aeschlyus's dramatisation of the myth of Prometheus, who stole the fire of the Gods for human use and was punished with eternal agony, bound to a rock where an eagle would feast on his regrowing liver every day.
The last paragraph of the book, with its classical reference, is challenging. On one hand, Hardy seems to be suggesting that Tess's life and story is a very small and insignificant game, or bit of 'sport', that has achieved nothing. By drawing the observer back to the level of the 'Immortals', he reminds us of that strange description of Tess being like a fly on a billiard table when she first arrives at Talbothay's dairy; she seems tiny and unimportant in the great scheme of things.
However, the reference also suggests that Tess and her story have a significance that goes beyond the time and place in which her story is set; like Prometheus, she too has strived to achieve something extraordinary and has been harshly punished for it, inviting the admiration, pity and sympathy of all who hear her tale. Perhaps she is a timeless, mythic character, or perhaps she is just a milkmaid who overstepped the social boundaries of her time. Hardy leaves it to us to decide.