How we cite our quotes: (Part.Chapter.Paragraph), with the exception of Part V, which runs (Part#. "Short Title". Paragraph). Part V has no numbered chapters—only title headings.
Quote #1
And then, while he was moving back and forth on her, he seemed incessantly to be describing the same movement, from childhood to adulthood and then in reverse, and once again from the little boy miserably gazing at the gigantic body of a woman to the man clasping that body and taming it. (II.11.16)
Karel is having a great time living out his childhood sexual fantasies on his mistress Eva's body. As a child, Karel had a little boy crush on Mrs. Nora, his mother's friend. But of course, he was too small to act on it. When his mother remarks that Eva looks a lot like Nora, Karel finds a new way to heighten his arousal: by turning Eva into Nora.
So while he's having sex with Eva (in his wife's presence), Karel is having a kind of metaphysical experience—leaping through time to indulge in those sexual fantasies of his boyhood days. Karel is really not interested in Nora or Eva as people: he's really all about "conquering," bringing something under control that has been out of his grasp for a long, long time.
Quote #2
The moment she removed his head from the body, she felt the strange and intoxicating touch of freedom. That anonymity of the body was a suddenly discovered paradise. With an odd delight, she expelled her wounded and too vigilant soul and was transformed into a simple body without past or memory, but all the more eager and receptive. (II.12.8)
While her husband Karel is engaging in some serious fantasy play during a threesome with Eva, Marketa decides to get in on the game. She finds herself generally not enjoying sex with her husband because, well, she loves him too much and he's a woman-chaser. Marketa has a hard time feeling pleasure because she feels the sorrow of being in such a crummy relationship.
But when she realizes she can take the weight of her sadness and all the problems of her marriage out of the bedroom by mentally decapitating her husband, things get a whole lot better. Marketa can focus on her own sensual pleasure when she doesn't have to worry about her husband's desire or reactions.
Quote #3
And I ran after that voice through the streets so as not to lose sight of the splendid wreath of bodies gliding over the city, and I realized with anguish in my heart that they were flying like birds and I was falling like a stone, that they had wings and I would never have any. (III.6.9)
Kundera turns his experience as a dissident into a metaphorical dance that he can't ever rejoin. He recalls the wonderful celebrations held when the Communists had a victory (including executions of "traitors"), and how people came together to dance in a circle. But after he falls out of favor, he can no longer participate in that exclusive brotherhood, though he can see others enjoying the whole Communist "idyll" right before his eyes.
In this case, Kundera describes his feelings of isolation and exile through the widening distance between himself and those who are still in the group—those people fly up into the heavens while he and his fortunes continue to sink. It's a metaphysical description, but it also neatly sums up how physically and mentally hideous Kundera feels at this time in his life.