All hail the great 17th-century nanotechnologist Assad Ullah!

Actually, he was a swordmaker, one in a long line of smiths who forged the legendary weapons known as Damascus sabers. They were strong yet flexible and supremely sharp, which European warriors first discovered, much to their misfortune, at the hands of Muslims during the Crusades.

The recipe for making Damascus steel was lost at the end of the 18th century, so no one knew the reasons for its remarkable qualities. But an analysis by 21st-century researchers in Germany provides a clue: Damascus sabers, they report in Nature, contain carbon nanotubes.

Using a transmission electron microscope, Peter Paufler of the Technical University of Dresden and colleagues looked at a very thin sample of steel from a saber made by Assad Ullah, who worked in what is now Iran. What they saw seemed for all the world like carbon nanotubes, cylindrical arrangements of carbon atoms first discovered in 1991 and now made in laboratories all over the world. Further analysis confirmed that that was what they were.

“If you look at the spacing of the atomic layers in these nanotubes,” Dr. Paufler said, “the spacing is the same as reported by others studying mass-produced nanotubes.”