When a presidential campaign often inhabits the gutter it’s not easy to establish its low point.

We’ve seen Donald Trump vilify Muslims, Mexicans and women. We’ve seen him indulge airy suggestions that rifle-bearing Americans might like to shoot Hillary Clinton. We’ve seen him belabor the lie that President Obama was not born in the United States — until he recanted. For Trump, the low road to the White House is paved with boorishness. But perhaps his son Donald Trump Jr. set the nadir this week when he compared Syrian refugees to a bowl of Skittles.

A caption accompanying a photograph of the candy said: “If I had a bowl of skittles and I told you just three would kill you. Would you take a handful? That’s our Syrian refugee problem.” Trump Jr. tweeted, “This image says it all.”

Where to begin? With the fact that human beings are not Skittles? With the fact that after more than five years of war 4.8 million Syrians are refugees and 6.1 million are internally displaced and Trump Jr., even with his coddled New York existence, can surely make the calculation that this amounts to almost 2.5 million more human beings than live in the five boroughs?

With the fact that you do not flee your home because you have a choice (like choosing between Skittles and M&Ms after a Manhattan dinner party) but because you no longer have one? With the fact that, according to a Cato Institute study of refugees admitted to the United States between 1975 and 2015, the chance of an American being killed in a terrorist attack committed by a refugee is 1 in 3.64 billion? With the fact that Syrians want to work, make a living, put their kids in decent schools, and recover their dignity, just like the rest of us?