For 15 years, the primary metaphor of the web has been pages and reading,” Borthwick writes. “The metaphors we used to circumscribe this possibility set were mostly drawn from books and architecture (pages, browser, sites, etc.). Most of these metaphors were static and one way. The stream metaphor is fundamentally different. [It’s] dynamic, it [doesn’t] live very well within a page and [is] still very much evolving.