“Watched Bush in Africa saying how bad slavery was and it really was,” said the e-mail I just received from this reader in Plantation, Fla. “How about writing a column about those bad African kings who sold their enemies to the slave-traders. Without their cooperation there would have been no slavery.”

I’ve heard that one a few times before. Indeed, in the nine years I’ve been doing business at this pop stand, that request has surfaced with death-and-taxes predictability everytime a condemnation of America’s role in the slave trade has made the headlines. So it was hardly surprising to receive Bruce’s e-mail soon after President Bush’s speech last week at Goree Island off the coast of Senegal, the point of embarkation for the journey of captive Africans to America.

The request is usually framed in such a way as to suggest the writer thinks the “news” of African complicity in the slave trade will take me by surprise. Maybe even knock me off my high horse a bit. They seem to find it somehow unreasonable to evoke America’s role in this obscenity. Why, they demand, don’t you ever mention that some Africans sold their own people?

Guys, you should be careful what you wish for.

Let us first stipulate the point. The leaders of various African ethnic groups sometimes sold to European slave traders fellow Africans who were being held as prisoners of war.

Let’s also stipulate the implied larger point: Where slavery is concerned, there is blame to go around.

We can blame the Netherlands, for instance; that nation’s government-chartered Dutch East India Co. was prominent in the business of transporting slaves.

We can blame Spain, Great Britain and Portugal, nations whose hands also are wet with African blood and tears.

We can even blame the Christian church, which allowed its gospel to be used as justification for the flesh trade.

Now, here’s the thing: What does any of that have to do with the price of beans in Boston?

Bruce raises what I call the “cookie jar defense.” Think of the kid, caught sitting on the kitchen counter elbow deep in the Oreos, whose first response is to snitch on his brother. “Stevie took some, too!”

Maybe so, kid. But right now we’re not talking about Stevie, we’re talking about you. And the fact that he is also guilty doesn’t make you any less so.

Similarly, there may come a time when we call to account African slave traders, the church, the Netherlands, Spain, Great Britain and Portugal for their sins in the years of slavery. But first, let us deal with America. That hardly seems unreasonable, given that its very existence motivated the crime, that it is the place where the deed was consummated, and that it reaped virtually all the benefits.

Most wondrous nation on earth, yes. But also a nation whose fields were tilled, whose grand homes were built, whose babies were suckled, by people in chains. No place I would rather be, no. But also a place that looked past rape, encouraged kidnapping, winked at murder. Sweet land of liberty, sure. But also a land that sold humans like horses, that whipped them like dogs and that is still, generations later, dealing with the ramifications of that sin.

The cookie jar defense only illustrates how difficult it is for some of us to come to terms with that inarguable, unalterable truth. The instinct is always to say, Yes, but…

Yes, but it wasn’t really as bad as they say.

Yes, but that’s in the past.

Yes, but the Africans did it, too.

I find myself wearied by the predictability of it, made impatient by the moral cowardice of people who have learned to do everything where this historical obscenity is concerned except one. Everything except deal with it.

For the record, some of us never had a choice.