The Aug. 6, 2001, president’s daily brief helps the nation’s understanding of what President Bush was being told a month before the 9-11 attacks. The memo on its own – one, short document among thousands – shows that the president knew al-Qaida cells were operating in the United States and that the FBI was conducting “approximately 70 full field investigations throughout the U.S. that it considers Bin Laden-related.”

But for the public to understand the importance of the Aug. 6 brief, titled “Bin Laden Determined to Strike in U.S.,” the 9-11 commission will have to add context. It will have the chance this week when it hears testimony and questions intelligence officials.

It should want to know, for instance, what 70 field investigations means. Does this number represent a high alert and, if so, how thoroughly was the president informed? Does it mean investigators were working night and day to try to figure out where al-Qaida would strike? Did the president take further steps or were these investigations all that could be reasonably expected? Several commission members urged that the Aug. 6 memo be made public. Now that it has, they have an obligation to also provide the background for it.

The president too should be more forthcoming. He said Sunday, “The [memo] was no indication of a terrorist threat. There was not a time and place of an attack. It said Osama Bin Laden had designs on America. Well, I knew that.”

But that is clearly not all the memo said. For instance, it said al-Qaida members had been living in the United States for years, apparently maintaining “a support structure that could aid attacks.” And while leaving unconfirmed the rumor that Mr. Bin Laden wanted to hijack an airplane to free terrorists, FBI information “indicates patterns of suspicious activity in this country consistent with preparations for hijackings or other types of attacks, including recent surveillance of federal buildings in New York.”

Planes. Buildings. New York. The memo is not nearly enough on its own to connect these dots when this information was approximate, at best, and so much other information was also present. The commission has been careful not to suggest anything the White House did or failed to do ensured the success of the 9-11 attacks. That is appropriate. But it should want to know how the administration was thinking about the contents of this memo and whether the investigations referred to produced a more specific warning that never made it to the White House.

The nation suffered tragic losses and a shock that reverberates today as a result of 9-11. Its domestic and foreign policies have been remade as a result. The question that can be fairly asked is whether the administration treated the contents of the Aug. 6 memo as the threat they turned out to be or whether the warning was lost in the noise of so much other information that summer.