My judgment that you need to see the Mohammed cartoons to really understand the controversy — and that verbal descriptions of the cartoons can't explain the matter well enough — reminds me of this similar tidbit about poetry (see Edward de Grazia, Girls Lean Back Everywhere 335-36 (1992)).
In the late 1950s, California prosecutors brought obscenity charges against the publisher of Allen Ginsberg's poem Howl. One difficulty, of course, was figuring out what exactly this poem meant, but fortunately — as often happens in obscenity cases — the defense produced an expert witness, literary critic Mark Schorer, to testify about the subject. Here's an exchange between him and the prosecutor:
Prosecutor: I presume you understand the whole thing, is that right?
Schorer: I hope so. It's not always easy to know that one understands exactly what a contemporary poet is saying. . . .
Prosecutor: Do you understand what "angelheaded hipsters burning for the ancient heavenly connection to the starry dynamo in the machinery of night" means?
Schorer: Sir, you can't translate poetry into prose. That's why it's poetry.