President Donald Trump's niece Mary not only spent her life around the president and his family, but she also has the benefit of being a psychologist who could legitimately assess the life and mental health of her uncle.

Speaking to MSNBC's Lawrence O'Donnell, she explained that in one particular moment in the Tuesday evening debate, Trump seemed triggered by former Vice President Joe Biden's use of the phrase "not smart" in reference to a policy. Trump went off.

"Did you use the word 'smart?'" Trump asked after Biden insulted Trump's coronavirus plan as not being "smart."

"So you said you went to Delaware State but you forgot the name of your college," Trump continued, falsely claiming something Biden never said. "You didn't go to Delaware state. You graduated either the lowest or almost the lowest in your class. Don't ever use the word 'smart' with me. Don't ever use that word."

Mary Trump explained that it was "classic projection" on the president's part. Even though the "not smart" had nothing to do with Trump himself, he couldn't control himself.

"Well, he knows [smart] doesn't apply to him, and he's very insecure about it," she said. "That was just classic projection because, you know, it also didn't make any sense. Joe Biden was talking about a tactic that wasn't the right way to approach something. He wasn't talking about anybody's IQ. So, I think it was just another example of Donald's insecurity coming to the surface.

O'Donnell noted that when Biden called Trump a "racist," he didn't bat an eye and didn't seem to care.

Mary Trump explained that it was "classic projection" on the president's part. Even though the "not smart" had nothing to do with Trump himself, he couldn't control himself.

"Well, he knows [smart] doesn't apply to him, and he's very insecure about it," she said. "That was just classic projection because, you know, it also didn't make any sense. Joe Biden was talking about a tactic that wasn't the right way to approach something. He wasn't talking about anybody's IQ. So, I think it was just another example of Donald's insecurity coming to the surface.

O'Donnell noted that when Biden called Trump a "racist," he didn't bat an eye and didn't seem to care.

"That was a great observation," noted Mary Trump. "No, he's happy to take that label as we saw with his horrific comments or failure to comment, I should say, on condemning white supremacy. He knows — first of all, he is a white supremacist, so he's not going to go condemn himself. And secondly, he knows that that is something about him that plays with his base, and his base is all he's got left."

Biden went after Trump's attacks on soldiers, talking about his late son, who served in Iraq. Trump pivoted from Biden talking about soldiers to attacking Biden's other son Hunter for his addiction struggle. Mary Trump said that her reaction to it was "pure rage."

"It was horrifying," she said. "It was certainly not the most dangerous moment in the debate, but I think it explains why other moments are as dangerous as they are. This shows us who he is. First of all, I found Vice President Biden's restraint absolutely incomprehensible. But that's who — that's who Donald is. He is cruel. He is contemptuous. And when Vice President Biden was able to steer the conversation back to something that mattered, his son's recovery, and to say how proud he was of his son, I first thought personally I wish he had been my father's dad. But unfortunately, Donald Trump was my father's brother, so it was a pretty devastating moment."

See the interview below:

Part 1:

Mary Trump youtu.be

Part 2:

Mary Trump 2 youtu.be