It is said that a traveler came to Baghdad and Haroun Rashid's court. He asked a few questions before the Khalifa to his viziers and wise men, but no one could answer correctly.
The Khalifa got angry and said to his scholarly courtiers and viziers, “If you people can't answer this person's questions, then I will give your entire wealth to him.”
Those present wanted 24 hours time, which the Khalifa gave. One of them said, “I think that we should seek out Bahlool. No one except he can give correct answers to this foreigner.”
So, they went to look for Bahlool and told him the whole story when they found him. Bahlool agreed to answer the foreigner's questions the next day. He addressed him, “Ask whatever you want. I am ready to answer.”
The man sketched a circle with his cane and looked at Bahlool.
Unhesitatingly, Bahlool drew a line in the middle of the circle, cutting it in half.
The traveler made another circle. This time Bahlool divided it into four equal parts, and pointing one out, he said to the man, “This one part is land, the other three are water.”
The traveler knew that Bahlool understood him and had given him correct answers. He praised Bahlool before the scholars, Khalifa, and all those present. Then he put the back of his hand on the floor and pointed his fingers toward the sky.
Bahlool did the opposite; he put his fingers facing the ground with the back of the hand upwards. The traveler praised him a lot, saying to the Khalifa, “You should be proud of keeping such an intelligent scholar.”
The Khalifa said, “I don't understand these questions and answers.”
The traveler explained, “I drew a circle. My purpose was to show the earth's being round. He understood and cut it into two pieces. He wanted to show me that he believed the earth was round, and that he knew its signs. He drew that line, making two equal pieces to show North and South. The second time I drew a circle, he divided it into four parts to show me that the earth has four parts. One part is land, while the other three are water. The third time when I put my palm and fingers facing upwards, my purpose was to show the growing plants and the secrets of their development. Bahlool also pointed his hand out as rain and the sun's rays and explained that the growth of vegetation is because of rain and sunlight. Therefore, you should be proud of such an intelligent person.”
The scholars and viziers were saved form Haroun Rashid's anger by Bahlool's ready, witty replies. They thanked Allah and Bahlool very much.