It is said that there was noneamong the Khalifs of the house of Abbasmore accomplished in all branches of knowledge than El Mamoun. On two days in each weekhe was wont to preside at conferences of the learnedwhen the doctors and theologians met and sittingeach in his several rank and roomdisputed in his presence. One dayas he sat thusthere came into the assembly a strangerclad in worn white clothesand sat down in an obscure placebehind the doctors of the law. Then the assembled scholars began to speak and expound difficult questionsit being the custom that the various propositions should be submitted to each in turn and that whoso bethought him of some subtle addition or rare traitshould make mention of it. So the question went round till it came to the strangerwho spoke in his turn and made a goodlier answer than that of any of the doctors；and the Khalif approved his speech and bade advance him to a higher room. When the second question came round to himhe made a still more admirable answerand the Khalif ordered him to be preferred to a yet higher place. When the third question reached himhe made answer more justly and appropriately than on the two previous occasionsand El Mamoun bade him come up and sit near himself.
When the conference broke upwater was brought and they washed their hands；after which food was set on and they ate. Then the doctors arose and withdrew；but El Mamoun forbade the stranger to depart with them and calling him to himselfentreated him with especial favour and promised him honour and benefits.
Presentlythey made ready the banquet of wine；the fair-faced boon-companions came and the cup went round amongst them till it came to the strangerwho rose to his feet and said'If the Commander of the Faithful permit meI will say one word.'Say what thou wilt，'answered the Khalif. Quoth the stranger，'Verilythe Exalted Intelligence（whose eminence God increase！）knoweth that his slave was this dayin the august assemblyone of the unknown folk and of the meanest of the companyand the Commander of the Faithful distinguished him and brought him near to himselflittle as was the wit he showed，preferring him above the rest and advancing him to a rank whereto his thought aspired not： and now he is minded to deprive him of that small portion of wit that raised him from obscurity and augmented himafter his littleness. God forfend that the Commander of the Faithful should envy his slave what little he hath of understanding and worth and renown！ Butif his slave should drink winehis reason would depart from him and ignorance draw near to him and steal away his good breeding；so would he revert to that low degreewhence he sprangand become contemptible and ridiculous in the eyes of the folk. I hope，thereforethat the August Intelligenceof his power and bounty and royal generosity and magnanimitywill not despoil his slave of this jewel.'
When the Khalif heard his speechhe praised him and thanked him and making him sit down again in his placeshowed him high honour and ordered him a present of a hundred thousand diners.
Moreover he mounted him upon a horse and gave him rich apparel；and in every assembly he exalted him and showed him favour over all the other doctorstill he became the highest of them all in rank.