​President Trump took credit for coining the phrase “priming the pump,” an expression ​that dates back to the 19th century and came into wide use ​during the Herbert Hoover administration in ​the 1930s​.

“Have you heard that expression used before? Because I haven’t heard it. I mean, I just … I came up with it a couple of days ago and I thought it was good. It’s what you have to do,” he told the Economist in an interview published on Thursday.

“Yeah, what you have to do is you have to put something in before you can get something out,” he said, explaining ​the concept​.

​But Merriam-Webster, in a tweet on Thursday, said the phrase dates to the early 1800s and has been used since at least 1933 to refer to “government investment expenditures designed to induce a self-sustaining expansion of economic activity.”

​The website Investopedia said the phrase originated with President Hoover’s creation of the Reconstruction Finance Corporation in 1932​ to give a jump start to the economy during the Great Depression.

The phrase came up during the interview when Trump was discuss​ing​ his tax plan proposal and its affect on the deficit.

“But, but it’s called priming the pump. You know, if you don’t do that, you’re never going to bring your taxes down,” Trump said.

He then asked the interviewers if they understood the expression​ ​and continued:

“We’re the highest-taxed nation in the world. Have you heard that expression before, for this particular type of an event?”

They said they had.

“Have you heard that expression used before? Because I haven’t heard it. I mean, I just…I came up with it a couple of days ago and I thought it was good. It’s what you have to do,” Trump said.​