The Symposium is a philosophical text by Plato that dates from about 385-380 BCE. It deals with the nature of love and, at a deeper level, with the nature of knowledge: how do we know what we know?
A symposium is a men’s drinking party. The section of the text which the narrator of Unbearable Lightness speaks about is presented by Aristophanes, the great comic playwright who is out of place in a meeting of philosophers and is depicted as being very drunk. The symposium scene below is a fresco from the Tomb of the Diver, now in the Paestum Museum in Italy.
Aristophanes explains that when people fall in love, they say they feel “whole” because they have found their other half. In primal times, he claims, people had double bodies, with faces and limbs facing away from each other. Being somewhat spherical and possessed of multiple limbs, they were very powerful and traveled about doing cartwheels. There were actually three sexes: male, female, and “androgynous” -- or half-man, half-woman.
When these creatures sought to ascend Mt Olympus to the home of the gods, Zeus chopped them all in half, thereby separating the two bodies. Ever since, each person has been searching for his or her other half.
Back in section 19 of Part Two, Tereza wrestles with her jealousy at Tomas's womanizing, when she yearns to merge with him into "a "hermaphrodite" (an intimation of Aristophanes' un-cleaved monsters) so that other women's bodies would merely become playthings for both of them.
As a female dog with a male name, who is referred to by the narrator as “he” for most of the book, Karenin is a sort of hermaphrodite figure in this book, who perhaps represents the kind of pre-human state of wholeness that the humans are looking for through love and sex.