Okay, can we just establish the fact that Mary and Olive ALWAYS know what each other means. There's no reason to say, "I know what you mean." Even though neither of them can verbalize the deep feelings and insights they experience at the world around them, it doesn't matter because the other will clearly understand. In fact, words don't need to be said at all. These two can just hang out together in complete silence, glancing at each other knowingly.