Which is to say: a lot.
Here is what Donald Trump chose to say to his supporters about his opponent at a rally:
“Hillary Clinton meets in secret with international banks to plan the destruction of global sovereignty in order to enrich these global interest powers, her special interest friends and her donors.”
And Trump's supporters applauded -- wildly.
Many political observers have commented on Trump's odd and ambiguous relationship with the Jews. I have defended him against charges of anti-Semitism, saying that he grew up in Jamaica Estates, Queens, in a Jewish area, and that he has many Jewish friends and associates.
(Fun fact: Some years ago, I found an old dinner dance journal from 1943, from the Jamaica Jewish Center, in which Donald's father, the similarly controversial Fred Trump, took out a full page ad "in honor of my friends at Jamaica Jewish Center.")
Many have pointed to his daughter Ivanka's conversion to Orthodox Judaism, and Trump's Jewish grandchildren, as proof that he cannot be anti-Semitic.
But then, there were those "hmmm ... " moments -- and they have been mounting.
- There were Trump's remarks before the Republican Jewish Coalition: "I know why you're not going to support me. You're not going to support me because I don't want your money. ... Look, I'm a negotiator like you folks ... "
And some said: Oh, he was just trying to be folksy and familiar.
- Then, there was: "Black guys counting my money! I hate it. The only kind of people I want counting my money are short guys that wear yarmulkes all day."
And, some said: Oh, he was paying Jews a compliment for their business acumen.
- Then, there was that business about Hillary Clinton and the Star of David.
And some said: Oh, that was just a six-pointed star -- like a sheriff's badge.
- Remember how Trump referred to comedian Jon Stewart? "I promise you that I'm much smarter than Jonathan Leibowitz - I mean Jon Stewart @TheDailyShow. Who, by the way, is totally overrated."
And, some Jews said to me: Trump was actually castigating Stewart for changing his name -- for being an assimilationist.
(Yeah, right. Donald Trump as the defender of Jewish identity against the forces of modernity.)
But, now the anti-Semitic needle starts to go into the red zone.
- There has been the constant barrage of anti-Semitic tweets and attacks on reporters who happen to be Jewish who have criticized Trump.
- There have been anti-Semitic attacks on New York state Attorney General Eric Schneiderman for his attention to the Trump Foundation.
No more apologies. No more forced explanations. No more convoluted rationalizations.
When you talk about global conspiracies, and when you use terms like "international banks," you are talking about the Jews.
Because there has never been another people in the history of the world that has been accused of global conspiracy.
It goes back to the infamous Protocols of the Elders of Zion, the forged czarist document that purports to uncover the Jewish scheme for world dominion. In this country, no less a person than Henry Ford was responsible for the dissemination of that horrific souvenir of anti-Jewish paranoia.
In fact, the very notion of "conspiracy" could not exist without the Jews. Take the word "cabal," which means a secretive group that works behind the scenes, usually for nefarious purposes.
"Cabal" comes from the word "kabbalah," the secret doctrine of Jewish mysticism, which anti-Semites considered so secretive that they were sure it contained hidden codes for Jewish domination.
I am still not accusing Trump of being anti-Semitic. I don't know what is going on inside his heart and soul.
But, all along, Trump has been sending anti-Semitic dog whistles -- the red meat of hatred that he has been throwing to many of his supporters.
At the risk of being uncivil in the midst of a campaign that has had no surplus of civility, their ideology is deplorable.
The dog whistle that Trump just sent -- the international Jewish conspiracy theme -- is the oldest one, and historically, it has been the most dangerous one.
If Trump doesn't know what he just said, he is not as smart as he thinks.
And if he does know what he just said, he is far worse than we had thought.
(Rabbi Jeffrey K. Salkin is the spiritual leader of Temple Solel in Hollywood, Fla., and writes the Martini Judaism blog for RNS)