That anxiety, in turn, reduces our ability to think effectively. He proposed a theory about how our minds work: when we try to keep track of obligations in our heads, we create “open loops” that make us anxious.

Allen combined ideas from Zen Buddhism with the strict organizational techniques he’d honed while advising corporate clients. The time-management system it described, called G.T.D., had been developed by David Allen, a consultant turned entrepreneur who lived in the crunchy mountain town of Ojai, California. It was titled “ Getting Things Done: The Art of Stress-Free Productivity,” and, for Mann, it changed everything. In 2003, he came across a book that seemed to address his frustrations.

“E-mail is a ball of uncertainty that represents anxiety,” Mann said, reflecting on this period. Work lives that had once been sequential-two or three blocks of work, broken up by meetings and phone calls-became frantic, improvisational, and impossibly overloaded. Many e-mails brought obligations: to answer a question, look into a lead, arrange a meeting, or provide feedback. With nearly all friction removed from professional communication, anyone could bother anyone else at any time. In the nineteen-nineties, the spread of e-mail had transformed knowledge work. “I was in this batting cage, deluged with information,” he told me recently. He had held similar roles for years, so he knew the ins and outs of the job he was surprised, therefore, to find that he was overwhelmed-not by the intellectual aspects of his work but by the many small administrative tasks, such as scheduling conference calls, that bubbled up from a turbulent stream of e-mail messages. In the early two-thousands, Merlin Mann, a Web designer and avowed Macintosh enthusiast, was working as a freelance project manager for software companies.

Getting Things Done by David Allen