So let's go to this point somewhere in between our initial and our final. Well, somewhere here, our rate begins to decrease going this way. In other words, because our concentration of X begins to slowly diminish, this guy begins to get smaller. And so, since this guy remains the same throughout the experiment going this way, that means our rate also begins to diminish going from X to Y. How about going from Y to X? Well, going from Y to X, our concentration of that product begins to increase.