It was getting too monotonous for Carl. Inaction of body allowed too great a freedom of mind. His days and nights were filled with thoughts of Sana, thoughts that became maddening as he realized the futility of life. Thoughts which made him more and more morose as the days went by. Only once did he show a mutual interest in the things that occurred about him. That was when one of the travelers called his attention to a beautiful oasis nearby, to which, however, the guides paid not the slightest attention. Questioned as to why the caravan did not stop, the guides replied to the effect that this was but a mirage of the Gurara Oasis, some five hundred miles away. For a few minutes they watched it, shimmering in the sunlight. Then it was gone as quickly as it had appeared. “Fata Morgana,” mused Carl, “Life and it are the same--just an illusion.” That night they reached Tenduf, having placed a thousand miles of desert behind them. The following day they reached the sand-hill region of Igidi. Here the desert looked as if on fire. The sands glowed red beneath the blazing sun. In the distance one could see great whirling clouds of sand, rising hundreds of feet in the air. The caravan halted. For a time it looked as if the storm would pass in another direction. Suddenly, however, it was upon them. The sky was darkened with the flying sand, the very ground itself seemed to be shifting under the fury of the storm. Instinctively the camels had lowered themselves to the ground. The travelers, under the direction of the guides, quickly threw themselves on the sands alongside of their beasts, covering themselves as best they could with their cloaks. For two long hours the storm raged--hours that seemed eternity to the suffocating men. Try as they would, they could not keep the dustlike sand from entering their eyes, nose and mouth. It was necessary, too, that they rise up for a minute or two to keep from being sanded in. [Illustration: The sky was darkened with the sand storm; instinctively the camels lowered themselves and the travelers threw themselves on the shifting sand, alongside of their beasts.] At last the storm was spent and the air once more fit to breathe. Man and beast stood up, shaking off their burdens of sand, to resume their journey. But thirty miles had been covered so far that day and they faced twenty more miles before they could rest. Carl was worn out. The storm and his general indisposition had got the better of him. It was with difficulty that he mounted his camel, and once up, it was harder still for him to keep awake. For a time he struggled with the desire to sleep, but it was useless.