Milan Kundera said this quote
“ They had been talking about his friend Z. when she announced, If I hadn't met you, I'd certainly have fallen in love with him.Even then, her words had left Tomas in a strange state of melancholy, and now he realized it was only a matter of chance that Tereza loved him and not his friend Z. Apart from her consummated love for Tomas, there were, in the realm of possibility, an infinite number of unconsummated loves for other men. We all reject out of hand the idea that the love of our life may be something light or weightless; we presume our love is what must be, that without it our life would no longer be the same; we feel that Beethoven himself, gloomy and awe-inspiring, is playing the Es muss sein! to our own great love.Tomas often thought of Tereza's remark about his friend Z. and came to the conclusion that the love story of his life exemplified not Es muss sein! (It must be so), but rather Es konnte auch anders sein (It could just as well be otherwise). ”