As the grandson of a Mexican immigrant —the kind of person who Donald Trump has described as a criminal, rapist and drug dealer, someone with “lots of problems”— I’m not eager to give the presumptive Republican presidential nominee credit for anything.

My grandfather arrived in the United States as a boy in about 1910, during the beginning of the Mexican Revolution. He came legally. This wasn’t difficult, given that one couldn’t come illegally until after the Immigration Act of 1924. The law established numerical limits on how many people could emigrate from specific countries. Before that, crossing the border was like going to the market.

Until Trump came along, I never thought of my grandfather as an example of what’s wrong with America. In fact, given his work ethic, eschewing of government handouts, and limitless optimism, I’ve always considered him —and other documented immigrants like him— to be part of what’s right with America.

That’s one reason I’ve been so tough on Trump. In the 11 months since he burst onto the political scene, I’ve called him a clown, demagogue, blowhard and snake-oil salesman. I’ve accused him of dividing Americans, bullying the defenseless and pandering to racists.

It’s in the last category that I would put the reader who recently characterized my criticism of Trump as “just another anti-American Latino rant by the token Washington Post Latino.” He went on to declare: “The Trump show is the greatest show on earth dude.” All this because, he said, “we are sick of illegals coming into this country, taking welfare dollars, expecting to receive free health care and schooling, and ignoring THE ENGLISH LANGUAGE! Go Trump!”

This is the type of person who has embraced Trump’s candidacy. Heavy on prejudice and snap judgments, light on facts and common sense.

Yet, to be fair, the billionaire does have one very important and impressive quality that helped him succeed in politics just like it did in business. It is something that is not often discussed on talk radio or cable TV shows. But this asset went a long way in helping him appeal to voters during what was a masterful primary campaign that vanquished 16 Republican opponents, many of whom, unlike Trump, had extensive political experience.

The attribute first came to my attention about eight months ago when I heard a former executive in the Trump organization say that the secret to the real estate mogul’s success was that he “knows people.” The former employee wasn’t talking about how many contacts are on Trump’s smartphone.

What he meant was that the businessman has a Ph.D. in human nature. He understands people, sometimes better than they understand themselves. He doesn’t just know what they think, but also why they think it. And he is an expert on actions and reactions.

While other Republican presidential candidates were playing checkers, he was busy playing chess and thinking three or four moves ahead. He knew that if he did “X,” his opponent would do “Y,” and that the voter would react by doing “Z.”

People talk about how those who aspire to the presidency have to be strong, or intelligent, or likable, or brave. But let’s not forget the importance of knowing your fellow man. With a skill like that, one can be anything in this world —including president of the United States.

Trump’s critics will acknowledge that he has this ability but they’ll claim that he uses it for evil purposes, as demagogues tend to do. Perhaps. Yet there is more to it than that. And it’s why, instead of cramming on policy, those who aspire to elective office would do well to bone up on psychology.

One of the things that made President Bill Clinton a natural at politics isn’t just that he could relate to people, and that he seemed to genuinely enjoy their company but also that, like Trump, he understood them. It’s a trait that Hillary Clinton would no doubt like to replicate, but she can’t seem to pull it off.

All of which raises an obvious question. Trump understood that many Americans worry that they’ve lost control of the borders and that undocumented immigrants take jobs, use services, and hurt people. So how could he have not understood that Hispanics would hear that overly simplistic pitch and be angered by his dishonesty and fear-mongering?

It’s good to have instincts about people. It’s better if those instincts extend to all kinds of people.