But how do you actually learn to hack? My family had settled in New Jersey by the time I was in fifth grade, and when I was in high school I went to the Borders bookstore in the Short Hills mall and bought “Beginning Visual C++,” by Ivor Horton. It ran to twelve hundred pages—my first grimoire. Like many tutorials, it was easy at first and then, suddenly, it wasn’t. Medieval students called the moment at which casual learners fail the pons asinorum, or “bridge of asses.” The term was inspired by Proposition 5 of Euclid’s Elements I, the first truly difficult idea in the book. Those who crossed the bridge would go on to master geometry; those who didn’t would remain dabblers. Section 4.3 of “Beginning Visual C++,” on “Dynamic Memory Allocation,” was my bridge of asses. I did not cross.