Sex toy or ISIS? Ever wonder what this black-and-white flag means?

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Marco Werman: Speaking of Syria, you've seen it, I've seen it - frankly, it's been hard to ignore this summer. I'm talking about the flag flown by the militants in Iraq and Syria, who call themselves the Islamic State. It's that black banner with white Arabic writing, the one you see online in images posted by the militants. I was curious about the origins of this banner, so for that I turned to Jonathan Bloom, professor of Islamic Art just down the road at Boston College. Let's start, Jonathan, by describing this flag. What does it look like? Jonathan Bloom: Well, it's a black rectangle and it has two, or sometimes three, lines of writing in white. The top one says "There is no god except for God." Then in the middle, there's a sort of rough circle that says "Muhammad is the messenger of God." Then sometimes below, you have a line of much fancier writing that says the state of the Islamic caliphate. Werman: It's become so iconic now that the sight of it instill fears. I suppose that's part of the propaganda of this flag. Bloom: I think the black color, which I guess we couldn't help, as Americans, thinking of as like a pirate flag. Werman: Right, well if you squint your eyes, it almost looks like the Jolly Roger. Bloom: Right, exactly. But I think for people who didn't grow up with buccaneers and such things, and certainly in the Islamic World, the black banner of Islam is an idea that goes back to the 8th century, when the Abbasid Caliphate, which was the second dynasty of Islam, came to power with black banners. Werman: So you're going back to the 8th century. That's a long history for this flag. Bloom: That's a long history and I think even the writing, the style of writing, are in a consciously primitive style of writing that harkens back to the very earliest day of Islam. It's meant to convey ancientness and antiquity. In effect, they're saying "We're going back to this earlier time." Werman: Speaking of graphics, let's talk about that white seal in the middle of this black flag. What are the origins of that seal? Bloom: It says "Muhammad is the Messenger of God." I think it's meant to invoke the Prophet seal, his signet, though I don't know that anybody knows what the Prophet seal actually looked like. But it's meant to convey this idea of a stone that's a seal. Werman: I know al-Qaeda flies a similar flag, at least to my untrained eye. Bloom: It uses the shahadah, that is the Arabic expression, "There is no god but God. Muhammad is the Prophet of God," which you find on the Saudi flag too. What's interesting is the black background and the choice of black over and over again, which I think harkens back to this much earlier type. Most of the flags in the Arab world today are red, green, white and black and these all go back to the early 20th century and Arab nationalism. Werman: As flags, as a symbol, do you think this is a successful one? Bloom: Graphically, yes. Without even knowing a word of Arabic, you can tell what it means. The iconography transcends the semantics of the words. Werman: It's also interesting too, I think of the Nazi swastika and how that was kind of ancient icon that was re-appropriated by the third reich. This is kind of doing the same thing. Bloom: Absolutely. If everyone starts identifying their use of this phrase, it's sending very much the wrong message, if we all accept that this is what that message means. They are co-opting something that has brought millions of people over thousands of years great comfort and solace and meaning in their lives. Werman: Jonathan Bloom is a professor of Islamic Art at Boston College. Thanks very much. Bloom: My pleasure.