With a key which he carried attached to a chain about his waist, he unlocked the ancient door which alone divided his shop from the outjutting wall marking a bend in the street. A native shop is usually nothing more than a double cell; but descending three stone steps, I found myself in one of those cellar-like apartments which are not uncommon in this part of Cairo. Windows there were none, if I except a small square opening, high up in one of the walls, which evidently communicated with the narrow courtyard separating Mohammed's establishment from that of his neighbor, but which admitted scanty light and less ventilation. Through this opening I could see what looked like the uplifted shafts of a cart. From one of the rough beams of the rather lofty ceiling a brass lamp hung by chains, and a quantity of primitive chemical paraphernalia littered the place; old-fashioned alembics, mysterious looking jars, and a sort of portable furnace, together with several tripods and a number of large, flat brass pans gave the place the appearance of some old alchemist's den. A rather handsome ebony table, intricately carved and inlaid with mother-o'-pearl and ivory, stood before a cushioned _dîwan_ which occupied that side of the room in which was the square window. "Set the box upon the floor," directed Mohammed, "but not with such undue dispatch as to cause thyself to sustain an injury." That he had been eagerly awaiting the arrival of the box and was now burningly anxious to witness my departure, grew more and more apparent with every word. Therefore-- "There are asses who are fleet of foot," I said, leisurely depositing my load at his feet; "but the wise man regulateth his pace in accordance with three things: the heat of the sun; the welfare of others; and the nature of his burden." "That thou hast frequently paused on the way from Shubra to reflect upon these three things," replied Mohammed, "I cannot doubt; depart, therefore, and ponder them at leisure, for I perceive that thou art a great philosopher." "Philosophy," I continued, seating myself upon the box, "sustaineth the mind, but the activity of the mind being dependent upon the welfare of the stomach, even the philosopher cannot afford to labor without hire." At that, Mohammed er-Rahmân unloosed upon me a long pent-up torrent of invective--and furnished me with the information which I was seeking. "O son of a wall-eyed mule!" he cried, shaking his fists over me, "no longer will I suffer thy idiotic chatter! Return to Abdul the Porter, who employed thee, for not one _faddah_ will I give thee, calamitous mongrel that thou art! Depart! for I was but this moment informed that a lady of high station is about to visit me. Depart! lest she mistake my shop for a pigsty." But even as he spoke the words, I became aware of a vague disturbance in the street, and--