A compelling Facebook photo shows an old man wearing spectacles and a shawl. He's standing in front of a cracked mud wall. Most of his face is filled by a huge, dusty-looking white beard. He looks tired and sad.
Only the man's family and friends would know that he is not, in fact, a weather-beaten mountain tribesman, but the vice chancellor of one of the most distinguished universities in Pakistan.
This picture of professor Ajmal Khan, posted on the Web by his supporters, was printed by a newspaper when he was freed, after spending four years as a hostage of the Taliban.