What metaphors are used in The Unbearable Lightness of Being by Milan Kundera?

The author says that Tereza’s body was a cage before she met Tomas, and “inside that cage was something which looked, listened, feared, thought, and marveled; that something, that remainder left over after the body had been accounted for, was the soul.” Thus Kundera manages to depict Tereza’s essence more deeply: her soul’s “closure” in her body until Tomas freed it.