Complementary

While doing a little art-theory research (I'm without much formal training, as is apparent), I came across this quote about complementary colors:

Complementary colors make a strange pair. They are opposite, yet they require each other. They incite each other to maximum vividness when together; and annihilate each other when mixed. — Johannes Itten

I have no idea who Mr. Itten is, but I love his words.