Don't take quotes literally. Its like a comparison between good and evil. If there is no good, then all there is evil or "nothingness". If there is no evil, then there is only good or only "nothingness". Think of it this way, if "good" was no longer in existance, there would be nothing to say as evil or a contrast towards doing the right thing. Same thing goes with "evil".
However, I can think of flaws with his comparison between love and hate. You can live with love in your life all the time, without hate. If you hate someone, fine, you can like them but not love them. People can hate you for many things, not only love. They can hate you for saying "Fuk u Hitler!!!" or calling you black.