Here is the letter Comey sent to the Congress today.

This analysis of why this happened and what the words of the letter actually says from Newsweek.

Why did FBI Director James Comey shock Washington on Friday with an announcement that the FBI "has learned of the existence of emails" related to Hillary Clinton's private email server, and what does it mean?

The truth is Comey didn't have a choice. Because the new information followed his sworn testimony about the case, Comey was obligated by Department of Justice rules to keep the relevant committees apprised.

Under oath Comey had stated that the bureau had completed its review. Once he learned that there were new emails that required examination, Comey had to notify Congress that he had to amend his testimony because it was no longer true.

Comey's letter to congressional committee chairs doesn't say his agents have discovered new witnesses or documents suggesting a criminal act occurred. Rather, he only suggests that evidence that has not yet been examined needs to be reviewed because it is relevant to the case.

There's also a political dimension. Had Comey not told Congress and it emerged after the election that new materials had come into its possession, the director and his entire agency's credibility might have been questioned.

In his letter, Comey did not use the phrase being touted by Republicans that the case had been reopened. Technically it was never closed. Nor did he signal at all about the importance or unimportance about the emails.

"In connection with an unrelated case, the FBI has learned of the existence of emails that appear to be pertinent to the investigation," he said in his letter to the chairs. "Although the FBI cannot yet assess whether or not this material may be significant, and I cannot predict how long it will take us to complete this additional work, I believe it is important to update you."

On the other hand, Comey did not offer any indication from whence the new evidence comes. By his omission he's left a country in suspense. Later in the day, news reports, unconfirmed by Newsweek, indicated that the emails were found in the course of an investigation of Anthony Weiner, the former New York congressman who is married to Clinton aide Huma Abedin, and that they were found on a device of Weiner's.

Others were not so forgiving of Comey.

Paul Krugman, Nobel Prize winner, and New York Times columnist, made clear his point of view.