Have you ever wondered where a phrase started? How about the phrase  prime the pump?  It is widely considered to mean the use of government money to get a project going. While it dates back to the 1800s, President Donald Trump is now claiming that he invented the phrase. In reality, the use of the phrase  prime the pump  predates Trump s own birth by a hundred years, and the use of it in the current economic sense has existed since the 1930s.In a recent conversation with The Economist, this exchange happened (they were talking about Trump s tax plan):The Economist: But beyond that it s OK if the tax plan increases the deficit? Trump: It is OK, because it won t increase it for long. You may have two years where you ll you understand the expression  prime the pump ? The Economist: Yes. Trump: We have to prime the pump. The Economist: It s very Keynesian. Trump: We re the highest-taxed nation in the world. Have you heard that expression before, for this particular type of an event? The Economist: Priming the pump? Trump: Yeah, have you heard it? The Economist: Yes. Trump: 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.According to The Free Dictionary:Prime the Pump: Encourage the growth or action of something, as in  Marjorie tried to prime the pump by offering some new issues for discussion.  In the late 1800s this expression originally was used for pouring liquid into a pump to expel the air and make it work. In the 1930s it was applied to government efforts to stimulate the economy and thereafter was applied to other undertakings.It is hardly surprising that a) Trump had never heard this phrase, as it is rarely used on Twitter and b) he would take credit for it. In a week with so many gaffes, lies and just strange behavior, this may not be as big an issue but it s clear how little this man knows and how little he understands the world and reality that the rest of us live in. Another explanation could be that Trump is much, much older than we have been led to believe and has gone completely senile.Featured image via Photo by Joe Raedle/Getty Images.