If you don't believe me, believe Josef Frank
“We should design our surroundings as if they originated by chance. It doesn’t matter if you mix old and new, or different styles, colours and patterns. The things you like will always blend, by themselves, into a peaceful whole.”
Josef Frank was a German textile designer who worked in Sweden. When I read this piece about him, I was blown away with how closely I agree with his design philosophy. He called it "Accidentism", which is to say that your home is made cohesive because all the things in it are things that you like. I've said this same thing to clients many times. "Don't worry-it'll all work together because you have chosen everything" (with varying degrees of belief on their part-haha!) Well, now I have a philosophy to quote!