“Thus for three nights,” continued Gazzar, fearing to cry for more anna, “they succeeded in robbing the treasury, taking from it many thousands of dinars and jewels. On the fourth night, however, a guard saw them hurrying away and gave the alarm. At that, Abou and Yussuf turned here and there in strange ways, Yussuf betaking himself to his home, while Abou fled to his master’s shop. Once there he threw off the disguise of a guard and reappeared as an aged vendor of rugs and was asked by the pursuing guards if he had seen anybody enter his shop. Abou motioned them to the rear of the shop, where they were bound and removed by Yussuf’s robber slaves. Others of the guards, however, had betaken themselves to their captain and reported, who immediately informed the treasurer. Torches were brought and a search made, and then he repaired to the caliph. The latter, much astonished that no trace of the entrance or departure of the thieves could be found, sent for a master thief recently taken in crime and sentenced to be gibbeted, and said to him: “‘Wouldst thou have thy life?’ “‘Aye, if thy grace will yield it.’ “‘Look you,’ said the caliph. ‘Our treasury has but now been robbed and there is no trace. Solve me this mystery within the moon, and thy life, though not thy freedom, is thine.’ “‘O Protector of the Faithful,’ said the thief, ‘do thou but let me see within the treasury.’ “And so, chained and in care of the treasurer himself and the caliph, he was taken to the treasury. Looking about him he at length saw a faint ray penetrating through the plate that had been loosed in the dome. “‘O Guardian of the Faithful,’ said the thief wisely and hopefully, ‘do thou place a cauldron of hot pitch under this dome and then see if the thief is not taken.’