Most of the natural systems, most of which concern humans anyway, are inherently chaotic. What that means, in the words of Edward Lorenz, is that although the present does determine the future, but the approximate present does not approximately determine the future. Simply put, this means that even minute variations in the initial conditions may yield incredibly diverging outcomes; this is also known as the butterfly effect. This presents an interesting problem for the human mind. It knows that the future can be predicted, given that the present (with all its zillions of variables) is perfectly known, but achieving perfect knowledge is an unending pursuit, mythical even.