You have right over here, the curve is flat. It's, you have right at that moment, you have no change in y with respect to x. Then it starts to decrease at a, then it decreases at an even faster rate, then it decreases at a faster rate. Then it starts, it's still decreasing, but it's decreasing at slower and slower rates, decreasing at slower rates. And right at that moment, it's not, you have your slope of your tangent line is zero. Then it starts to increase, increase, so on and so forth. And it just keeps happening over and over again.