Plato's Symposium is all about love. More specifically, it is a series of arguments used to define exactly what love is. For example, Phaedrus defines love as wisdom, virtue, moderation, orderliness, or anything beautiful, like music, art, and medicine, while Aristophanes defines love as purely the sexual desire that makes us long for and look for our other halves, and Socrates gives a completely different definition.
While romantic love is a very minor theme in Sophocles' works, like Antigone, we certainly can see that both the Symposium and Antigone share the theme of romantic love in common. Sophocles' Antigone is more of a reflection on which is more important, the gods' laws or man's laws, and also on human character flaws, such as pride, arrogance, and stubbornness. However, Creon's son Haemon is betrothed to Antigone, so Antigone's decision to bury her brother followed by Creon's own decision to execute her brings up the nature of Haemon's love for Antigone. If we were to characterize Haemon's demonstrated love for Antigone by one or more of the arguments defining what love is found in the Symposium, we could say that Haemon's love could be characterized by both Aristophanes' and Socrates' arguments. Aristophanes uses a myth to describe love as the type of erotic love in which one believes he/she is looking for his other half. It's clear that Haemon feels Antigone is his other half due to the fact that he cannot bear to be parted from her. He would rather die with her in the stone tomb than keep living without her. Socrates' argument serves to define love as a desire for what is wise and beautiful. We clearly see Haemon's desire for both what is wise and beautiful in his professed love for Antigone. He tries to convince is father Creon that he is being foolish to punish Antigone because it is foolish to place mankind's own laws above the laws of the gods; it is also foolish for a ruler not to listen to his/her own citizens' opinions, and Haemon knows all of the citizens feel Antigone should be praised as a hero for honoring the gods and not killed as a traitor. In trying to convince his father to listen to reason and release Antigone, Haemon is pursuing what he believes to be true and virtuous, and what is virtuous is also beautiful. Hence, in trying to save Antigone due to his love for both her and what is virtuous, he is doing what Socrates defines love as--pursuing virtue, which is something that's beautiful. Haemon is also being very wise to agree with Antigone that the gods' laws should be obeyed above man's laws; hence, through his love for Antigone, he is also pursuing wisdom, which is again what Socrates defines love as. We can best see Haemon's pursuit of both wisdom and virtue when he reprimands his father for being so stubborn that he listen's to no one else's counsel but his own in Haemon's lines:
Whoever thinks that he's the only one who can think or use his tongue or soul, no one else--these men, when you open them up, are seen to be hollow. (717-20)
We further see Haemon's pursuit of both wisdom and virtue when he points out that his father is not ruling his kingdom by disobeying the gods, turning the kingdom over to be destroyed by the gods' wrath:
You don't protect [your own empire] when you trample the honors of the gods! (756-57)
Hence we see that while Antigone is ultimately very different from the Symposium, the philosophy defining love can certainly be found in Antigone and could have influenced the philosophies and definitions of love found in the Symposium.