Ted Cruz’s refusal to endorse Donald Trump last night was a remarkable moment in political history. The end of Cruz’s speech was drowned out by the angry boos of disappointed Trump delegates. Cruz grinned tightly and pushed on. This morning, he said he was “not a servile puppy dog,” and that after Trump had insulted members of his family, weeks ago, he no longer felt any obligation to support him.

The scene was remarkably similar to one 52 years ago, in another Republican convention. Barry Goldwater, who had a knack for drawing the support of hate groups to his campaign, and who casually threw around talk of nuclear war, was set to clinch the Republican nomination. He motivated passionate dissent from within his own party, including from the runner-up of the Republican primary, the more liberal Nelson Rockefeller. Rockefeller, then-governor of New York, used his convention slot to make a point. The result sounded a lot like 2016. Or rather, Ted Cruz’s audience sounded a lot like Nelson Rockefeller’s. Take a look at some documentary footage of the convention and see if it doesn’t remind you of Wednesday night: