Yet some people doubt the effectiveness of either re-education or high-profile penitence in reducing the jihadist urge.

ECONOMIST: Public repentance

The season of Lent is marked by fasting and acts of penitence for past sins, with worshippers marking a cross on their foreheads with wood ash to symbolise human mortality.

BBC: Pope Benedict holds last public Mass

It opened in 1829 and was based on the philosophy that isolating inmates gave them a useful opportunity to get closer to God and to offer penitence (like "penitentiary, " get it?) for their crimes.

CNN: No kid should be in solitary confinement

This shows Midas on his throne, receiving the counsels of Ignorance and Suspicion, with a hooded Envy clasping the hand of Calumny, who in turn, with Deception and Fraud attending, is dragging the unidentified victim by the hair, while Penitence turns hopefully towards stark-naked Truth.

ECONOMIST: Botticelli and his bankers