Hal Abelson co-wrote Structure and Interpretation of Computer Programs, the book that taught a generation that programming is about controlling complexity rather than learning a language. Written with Gerald Jay Sussman for MIT's introductory course and published in 1985, it used Scheme not because Scheme mattered but because its near-absence of syntax let the ideas show: abstraction, recursion, higher-order procedures, streams, and — in its last chapters — building an interpreter for the language you are writing in. The wizard on the cover made it iconic; the difficulty made it divisive. MIT eventually replaced the course, and the book remains in print and in argument. Abelson has spent his career at MIT working on computation as a public good. He was a founding director of both the Free Software Foundation and Creative Commons, helped create MIT OpenCourseWare, and led App Inventor, which lets people with no programming background build Android applications. In 2013 he chaired MIT's internal review of the university's conduct in the Aaron Swartz prosecution.