To grasp something new, you must first let go. To learn, you must forget. Learning is not about acquiring knowledge and yet more knowledge. Learning is about leaping beyond your subjective self, about seeing things from a higher summit. And from there, it is an entirely new world. Yet as high a summit as you may reach, there is always another peak above. And you can only reach that higher peak once you realize you are still in the valley. The Talmud tells of Rabbi Zeira, who fasted one hundred fasts to forget his...