The banal spectacle that was the first night of the Democratic National Convention should remind Barack Obama and his liberal apostles to refrain from criticizing the rich as they endeavor to impose the Democrat candidate’s socialist policies on the nation.

The latest rich man to invite Mr. Obama’s fire is, of course, Republican John McCain. Mr. McCain, who is married to a beer heiress, much as Sen. John Kerry is married to a ketchup heiress, owns seven homes. Excessive this may be, and it did Mr. McCain no good when he said he couldn’t remember how many homes he had. Unsurprisingly, Mr. Obama pounced on that one.

“If you don’t know how many houses you have, then it’s not surprising that you might think the economy is fundamentally strong,” he said. “But if you’re like me, and you got one house, or you are like the millions of people who are struggling right now to keep up with their mortgage so they don’t lose their home, then you might have a different perspective.”

That would ring true with most Americans, but closer scrutiny reveals yet another of Mr. Obama’s hilarious gaffes. For one thing, that “one house” boasts a solarium, four fireplaces, a 1,000-bottle wine cellar and granite-floored kitchen. It’s worth about $1.6 million.

For another, the same day that Mr. Obama ridiculed Mr. McCain, readers around the world, of which Mr. Obama is a citizen, learned that his half-brother, George, lives in abject penury in a hovel in Kenya. George Obama says he spends about a dollar a month. “I have had to learn to live,” the candidate’s half-brother told the Italian edition of “Vanity Fair,” “and take what I need.”

So there was Mr. Obama blasting Mr. McCain for his wealth, even as Mr. Obama, who wangled a sweet real estate deal for his Georgian mansion from a man later convicted on corruption charges, permitted a half-brother to languish in African squalor. You wonder how much hope George Obama has.

Then we have Monday night’s tribute to Sen. Edward M. Kennedy. This film about the “Liberal Lion of the Senate” opened and closed with footage of Mr. Kennedy and his loved ones sailing on one of Mr. Kennedy’s boats, this one a fine craft of undoubtedly inestimable value.

One wonders what the Democrat reaction would be if Mr. McCain or another Republican weren’t helping a pauper relative, or if they were depicted as Mr. Kennedy was. Actually, one doesn’t wonder. Everyone knows. The Democrat response would be similar to Mr. Obama’s remarks about Mr. McCain. Republicans are “out of touch” with regular Americans.

Point is, now is the time for Mr. Obama to engage Mr. McCain on the issues, not snipe at his opponent’s good fortune, which Mr. Obama shares himself. Mr. Obama may not be as rich as Mr. McCain, but he is richer than most, and that means he and his followers ought to stifle the talk about Mr. McCain or anyone else with means beyond the average American.