Comey quickly confirmed where the last few weeks seemed to have been leading: There is no evidence to back up Trump's claim that Obama ordered wiretapping of his Trump Tower phones.
"I have no information that supports those tweets," Comey said.
Comey's clear-as-day comments make it impossible for Trump to keep saying he was "wiretapped".
But really, the whole wiretapping thing felt like a sidebar in this hearing to the FBI's broader investigation into Russia and any Trump associates' ties. That's in part because most lawmakers feel it IS a sidebar to the real issue: A foreign country interfered in a US election with the intent of undermining the United States' political process.
"The stakes are nothing less than the future of our democracy and liberal democracy," said Congressman Adam Schiff, the top Democrat on the committee.
So let's get into that.
2 The FBI is investigating connections between Trump's campaign associates and the Russian Government
This might seem to be an obvious takeaway. News organisations reported this two months ago.
But members of Congress have been extremely frustrated that, until today, the FBI has refused to privately acknowledge the existence of an investigation, let alone what it is looking into. (The FBI rarely acknowledges publicly the existence of an ongoing investigation except, in Comey's words, in "unusual circumstances".)
This, apparently, is one of those circumstances. Today, Comey told Congress and the world that, yes, the FBI is investigating Russia's meddling in the US election. In addition, it is investigating whether there was any coordination between the Trump campaign and Russia and "whether any crimes were committed".
3 But the FBI is going to be VERY tight-lipped about the investigation
In the next breath, Comey said he is not going to share much else about the investigation other than it exists: "We just cannot do our work well or fairly if we start talking about it while we're doing it."
And he cautioned Congress and the public not to read too much into the FBI's silence about it: "I know speculating is part of human nature, but it really isn't fair to draw conclusions simply because I say that I can't comment."
A caution Trump himself did not seem to heed in this tweet:
"FBI Director Comey refuses to deny he briefed President Obama on calls made by Michael Flynn to Russia."
Throughout the hearing, Comey would stay true to his word, especially when lawmakers asked about what investigators knew with regard to Trump officials: "I really don't want to get into answering any questions about any US person," he said at one point.
4 Democrats seem pretty sure associates with Trump's campaign colluded with Russia
Here's what we know about Trump's campaign and Russia:
The intelligence community has concluded that Russia meddled in the US election to undermine faith in the democratic process and harm Hillary Clinton's candidacy, in part because Russian President Vladimir Putin blamed then-Secretary of State Clinton for domestic protests against his authority in 2011-2012.
Two members of Trump's inner circle - former national security adviser Michael Flynn and Attorney-General Jeff Sessions - have publicly acknowledged that they failed to disclose private conversations with the Russian ambassador to the United States. Flynn lost his job; Sessions agreed to recuse himself from the FBI's investigation into Russian meddling in the US election as a result.
But meeting the Russian ambassador to Washington isn't illegal - in fact, you could argue it's part of diplomacy. It's the lack of disclosure that got both men in trouble.
Democrats are suggesting that Russia's involvement in the election and Trump officials' lack of disclosure about their ties to Russia point to something more. In a 15-minute opening statement, Schiff laid out a series of ties between Trump's campaign and Russia, citing former British spy Christopher Steele, who compiled an unverified dossier on Trump and Russia. They included accusations that:
One of Trump's national security advisers during the campaign, Carter Page, has ties to Russia and has praised Putin.
Former Trump campaign manager Paul Manafort had been on the payroll for pro-Russian interests in Ukraine.
Trump officials met the Russian ambassador to Washington during the Republican National Convention. At that convention, Republicans changed their platform to remove a section that supported giving weapons to Ukraine as it battles Russia for territory.
Former Trump adviser Roger Stone boasted in a speech that he knew of impending WikiLeaks documents related to Hillary Clinton's campaign before they were published.
And Flynn and Sessions would go on to avoid disclosing their conversations with the Russian ambassador during or shortly after the campaign.
After spelling all that out, Schiff (rhetorically) asked this:
"Is it possible that all of these events and reports are completely unrelated and nothing more than an entirely unhappy coincidence? Yes, it is possible. But it is also possible, maybe more than possible, that they are not coincidental, not disconnected and not unrelated, and that the Russians use the same techniques to corrupt US persons that they employed in Europe and elsewhere. We simply don't know. Not yet. And we owe it to the country to find out."
Comey and Rogers would not comment. But we know what Democrats have concluded.
5 Republicans want to focus on intelligence leaks to the press
If Democrats' line of questioning focused on alleged Trump ties to Russia, Republicans zeroed in on charges that someone in the intelligence community was leaking these intelligence reports to the media.
Congressman Trey Gowdy stressed that the leaks may have been politically motivated to weaken the Trump Administration.
This has the potential to be a major point of friction between Democrats and Republicans on the House Intelligence Committee as it pursues its own investigation into Russian meddling: Should the committee put more effort into finding out who leaked the information than whether there is any evidence of collusion between the Trump campaign and Russia?
6 Intelligence officials still don't think there's any evidence Russia's meddling directly influenced votes
Early on, Congressman Devin Nunes, the committee chairman, asked Rogers and Comey whether they had any evidence that Russia actually changed the vote tallies in key states.
Both men said there is no evidence that Russian meddling actually changed votes, something they also said in a January Senate hearing.
To some degree, the laser focus on vote tallies is a straw man argument, points out the Washington Post's Aaron Blake: It's nearly impossible to hack voting machines, and intelligence reports never implied that happened.
But Republicans like Nunes also can't emphasise enough that Russia's meddling to help Trump win probably did not actually help Trump win. They do this to underscore the legitimacy of his presidency, yes, but also to get Trump to recognise his own legitimacy.
Trump was originally hesitant to even acknowledge Russian meddling. He since has acknowledged it, but Republicans (and the intelligence community) need his full support to continue to investigate this, wherever it leads.
