In the very early hours of Tuesday morning, Pierre Poilievre delivered an extraordinary speech to the few hundred Conservative faithful still gathered in the loveless embrace of a slick downtown Ottawa convention centre.

It reminded me of something else I once saw, but we’ll get to that.

By the time Mr. Poilievre appeared on election night, several seats were still in flux, but it was clear that Canada’s next government would be Liberal. Again. Somehow. Incredibly.

The Conservative Leader delivered an election result better than expected, given how Donald Trump upended the political landscape. And that outcome was nowhere near the crushing Conservative majority that seemed certain just months ago, when Mr. Poilievre was the prime minister in-waiting and the actual prime minister was a dead man walking.

But Mr. Poilievre did not arrive on the stage in that room full of blue to deliver a concession speech. After paying tribute to his wife, Anaida, he thanked Conservative candidates, volunteers and supporters, and then laid it on the line immediately: I’m not going anywhere, and this isn’t over.

“It will be an honour to continue to fight for you and to be a champion of your cause as we go forward,” Mr. Poilievre told the party that had chucked its past two leaders out a window after a single election loss.

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He emphasized that Canadians had voted for “a razor-thin minority government, a virtual tie in the vote count,” though by morning, that wouldn’t be the case. Mr. Poilievre congratulated Prime Minister Mark Carney, and when the crowd booed, the Conservative Leader quelled them by saying the time would come to hold the government to account, but the country came first.

“Conservatives will work with the Prime Minister and all parties with the common goal of defending Canada’s interests and getting a new trade deal that puts these tariffs behind us, while protecting our sovereignty and the Canadian people,” Mr. Poilievre said.

Somewhere, there’s an alternate universe in which he said that or something similarly magnanimous back in November or March or two weeks ago. It‘s hard not to wonder what might have changed if he had.

He outlined how the loss was really a win if you looked at it right, telling his fellow Tories that they had “much to celebrate,” gaining more than 20 seats and landing the largest share of the popular vote since Brian Mulroney’s 1988 landslide.

“We hear your stories, we will carry those stories with us into Parliament,” he said. He must have known, even as he said it, that he had lost his own Carleton riding to a newbie Liberal and wouldn’t be returning to the House of Commons himself, at least not right away.

There was another time when that sprawling suburban-rural region on the edge of Ottawa voted for an upstart and turfed a political veteran.

The day after that election, in 2004, CPAC interviewed a panel of newly elected MPs, and the host began by introducing the Conservative rookie who had just toppled Liberal cabinet minister David Pratt as “a bit of a giant killer.” And there sat 25-year-old Mr. Poilievre, with chubby cheeks, owlish glasses and a too-big suit jacket.

Canadian voters had just handed a bedraggled Liberal government a fourth-term minority, and the newly united Conservatives under Stephen Harper had come up short of expectations. When the host asked about this, that freshman version of Mr. Poilievre instantly framed that loss as a victory, too: It was the best popular vote a centre-right party had achieved since 1988, he said, and they’d gained more seats than anyone else.

He argued that this new Parliament needed to democratize things, because there had been a corrosive concentration of power in the Prime Minister’s Office. And he wanted to “give people the right to fire their members of Parliament by petition if they break their word,” which he would propose in a private member’s bill.

“That‘s exactly the genius of our party, is that you have the ability to speak up as an individual member of Parliament,” he said, adding, “These are the kinds of things that Liberal members of Parliament are not able to do because of the intense party discipline that comes down from the top.”

Earlier this year, Mr. Poilievre told Jordan Peterson that he’s never changed his mind on anything. And it is certainly some kind of remarkable that the same points he was raising in teenage letters to the editor or an undergraduate essay about becoming prime minister are, almost verbatim, how he fought this election campaign to try to land that job in real life.

But it‘s not quite true that all of his ideas are bolted to the floor. He used to believe that there was too much top-down control of MPs, and then at some point, he became a party leader who refused to allow local candidates to do interviews or debates, and doled out speaking time to his caucus as a reward for following instructions.

Sometimes, it seems, we grow in ways that surprise even us.

The real message that the present-day Mr. Poilievre wanted to bring home on election night was the idea he underlined over and over again: A big shift doesn’t happen all at once, and you have to be patient enough to let it unfold.

In that inky postmidnight hour, when they were still tallying the ballots but the answer that counted was already clear, Mr. Poilievre was trying to persuade his party that this result, in all its hijacked strangeness, was a down payment on a victory deferred. He was good for the rest if they would just wait a while and put their knife-sharpening kits away.

“I know that some of you might be disappointed that change did not get over the finish line tonight. Change takes time,” he said. “Most of all, it requires that we never give up, because our people and our country are worth fighting for.”

This wasn’t something 25-year-old Pierre Poilievre had given attention to in that long-ago interview. The way time stretches and slips, and the value of second chances, doesn’t shape a young man’s view of the world like it does when you’re older.