The ethical obligation to run a Web search engine without advertising reflected an academic’s belief in the importance of public access to information, which could be a matter of life and death. In a remarkable appendix to that 1998 paper, “The Anatomy of a Large-Scale Hypertextual Web Search Engine,” Brin and Page offered an example of the danger to the public from search results that were tainted by advertising. As a test, they typed in the query “cellular phone” at all the prominent search sites. Only the Google prototype, they reported, returned a top result that was critical of cell phones, specifically a cautionary study about speaking on the phone while driving. PageRank didn’t return the link in order to do the right thing, the two explained; it was simply conveying to its users what the Web thought were the most relevant links to someone interested in cell phones. The better question to ask was, Why didn’t the other sites link to that study? Page and Brin’s answer: “It is clear that a search engine which was taking money for showing cellular phone ads would have difficulty justifying the page that our system returned to its paying advertisers.”