Gordon’s selection of this passage as Batman’s eulogy is quite apt. First of all, the lines in the book represent the last thoughts of the character Sydney Carton as he prepares to make the ultimate sacrifice for his loved ones and city—a sacrifice just like the one Batman makes. At the end of the novel, Carton manages to switch places with the character Charles Darnay as Darnay faces execution. As he does so, he expresses faith in his city, just like the faith Batman expresses for Gotham again and again throughout the Batman trilogy. Here’s the passage that comes just before those last lines:
I see a beautiful city and a brilliant people rising from this abyss, and, in their struggles to be truly free, in their triumphs and defeats, though long to come, I see the evil of this time and of the previous time of which this is the natural birth, gradually making expiation for itself and wearing out.
Intertextuality is only a part of mimesis, by the way, but nevertheless, it is a vital one. What’s awesome about this is that this is a very present model of what to look for in reading ancient literary texts. Intertextuality, allusion, and imitation are all ways or preserving past literary texts by making use of them in the present.