39. A lifestream is a sequence of all kinds of documents — all the electronic documents, digital photos, applications, Web bookmarks, rolodex cards, email messages and every other digital information chunk in your life — arranged from oldest to youngest, constantly growing as new documents arrive, easy to browse and search, with a past, present and future, appearing on your screen as a receding parade of index cards. Documents have no names and there are no directories; you retrieve elements by content: "Fifth Avenue" yields a sub-stream of every document that mentions Fifth Avenue.
40. A stream flows because time flows, and the stream is a concrete representation of time. The "now" line divides past from future. If you have a meeting at 10AM tomorrow, you put a reminder document in the future of your stream, at 10AM tomorrow. It flows steadily towards now. When now equals 10AM tomorrow, the reminder leaps over the now line and flows into the past. When you look at the future of your stream you see your plans and appointments, flowing steadily out of the future into the present, then the past."