never the twain shall meet
(idiomatic) Used to emphasize that two subjects are so different that they cannot coexist or agree with each other.
No, no, no separate but equal... never the twain shall meet. And the pendulum kept swinging and it came to rest in the bastard hybrid known as the Daily Show. Mo Rocca
Oh, East is East, and West is West, and never the twain shall meet. Rudyard Kipling
Oh, East is East, and West is West, and never the twain shall meet... (Rudyard Kipling) English Proverb