It is undeniable that today millions of people use computers as aids to their thinking. In the digital age, computers are an essential and intertwined supplement to our thoughts and our memories. Discussing Licklider’s prophesy from half a century ago, legal scholar Tim Wu notes that virtually every computer “program we use is a type of thinking aid—whether the task is to remember things (an address book), to organize prose (a word processor), or to keep track of friends (social network software).” These technologies have become not just aids to thought but also part of the thinking process itself. In the past, we invented paper and books, and then sound and video recordings to preserve knowledge and make it easier for us as individuals and societies to remember information. Digital technologies have made remembering even easier, by providing cheap storage, inexpensive retrieval, and global reach. Consider the Kindle, a cheap electronic reader that can hold 1,100 books, or even cheaper external hard drives that can hold hundreds of hours of high-definition video in a box the size of a paperback novel.