"Well, Art is Art, isn't it? Still, on the other hand, water is water. And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now you tell me what you know"

This quote by Groucho Marx is a funny way of explaining the absurdity of trying to compare two things that are totally different. He is saying that art is art and water is water, and that east is east and west is west. He is likewise making a joke about how if you take cranberries and stew them like applesauce, they taste more like prunes than rhubarb does. He is implying that no matter how hard you try, you can't make 2 completely different things the very same. He is also suggesting that no matter how much you know, there are some things that you simply can't explain. This quote is a tip that some things are just beyond our understanding.