Merlin Mann:
Put to best use, Inbox Zero is merely a philosophical practice of learning to be parsimonious about which and how many inputs we allow into into our lives—and, then, to responsibly but mindfully tend to those inputs in a way that is never allowed to hinder our personal commitment to doing the work that really matters to us.
To paraphrase Robert Louis Stevenson: Inboxes are good enough in their own right, but they are a mighty bloodless substitute for work.