Five days had thus passed, and there seemed no possibility of the Caliph escaping the painful and humiliating death to which he was destined by the heathen king. The festival to be held in honour of the gods of the country was approaching, and two days hence the people, who were already becoming greatly excited, both by religious fury and also by drinking great quantities of a strong and fiery spirit which they distilled, were to be gratified by the sight of the sacrifice by horrible tortures of their unfortunate prisoners.

Just before daybreak on the sixth day, the same morning on which Selim and his jailer were effecting their escape, the Caliph awoke, and thoughts of the frightful situation in which he found himself prevented him from again falling asleep. In great distress of mind he prayed earnestly to God that strength might be given him to enable him to sustain with firmness and fortitude the pains he might be called upon to endure. After which prayer he felt calmer and more composed. Presently, being very hungry, he tried in the dim light to find a small piece of bread which he had not yet eaten. He had placed it on a narrow ledge near to the place where he slept, but in the darkness he pushed it with his hand before he had grasped it, and it fell upon the floor. Groping about to find it, his hand came suddenly upon something which felt soft and cool—an object apparently about the size and shape of a hen's egg, yet not hard like an egg-shell, but elastic and yielding readily to the pressure of the fingers. What it was the sense of touch did not enable him to guess, and as yet the light was insufficient to permit him to distinguish anything clearly. And, marvellous to relate, as the light increased, although all the objects around him became visible, yet this something which he had felt, and which he still felt to be grasped in his hand, was nevertheless not to be seen. This circumstance surprised the Caliph very much, and he sat cross-legged on the straw which had been placed in the corner of the dungeon for him to sleep on, just as he had been used to do on the splendid divan in his palace, still grasping the unknown object in his hand, and yet still unable to see what it was. After he had sat thus for some time cogitating what this might mean, the hour came round when the jailer should come and bring him his food for the day.

Now it so happened that the Caliph's jailer when bringing his food had to pass the dungeon in which Selim had been confined. This morning as he passed he was amazed to observe that the door was unfastened, and, looking in, he perceived that the vault was empty. Fearful that his prisoner might likewise have effected his escape, he hurriedly set down the food and ran on to the dungeon containing the Caliph.

The latter was surprised to hear his jailer running rapidly along the passage, and still more surprised when the man, after looking through the panel, withdrew the huge bolts and, opening the door, came into the great gloomy vault, looking excitedly about him. Then after a few moments, apparently bewildered and terror-struck, he turned about, went out, closed the door behind him, and, without waiting to replace the bolts, walked quickly along the passage and disappeared.

The Caliph, although unable to guess to what he owed his good fortune, did not neglect to avail himself of it. Pushing open the door, and stopping to close it and bolt it behind him, he walked down the corridor without knowing where and to what it might lead him. This passage or corridor seemed at first sight to terminate with a dead wall at the end of it. But, proceeding further along it, he presently perceived a side-passage turning out of it at right angles, and this smaller passage, which was short, terminated in a flight of steps leading evidently into the castle-yard. The door at the top of the steps was partly open, and when he reached it the Caliph could hear and catch glimpses of a group of soldiers standing and chatting together not far from the doorway. He stood for some moments uncertain what he should do. If he opened the door and went out, doubtless he would immediately be seized; on the other hand, to stay where he was meant no less certain destruction, as at any moment some one might enter and find him there. He had just determined to step out boldly and risk detection, in the hope that in the bustle of the castle-yard his exit might pass unnoticed, when a gust of wind blew the door wide open, and he stood face to face, not ten paces distant, with that group of soldiers he had heard conversing.

For a moment he stood horror-struck, expecting to see them rush forward and secure him. To his extreme surprise, none of them, not even those facing him, took the slightest notice of his presence. They appeared not even to see him, but perhaps they took him for one of the innumerable retainers of the Court; at any rate, the Caliph, plucking up courage, stepped out and walked quietly away.

As he was crossing the courtyard, a great mounted warrior on a powerful black steed came pounding along, and would apparently have ridden right over the Caliph just as though he was unaware of his existence, but Haroun drew quickly aside, and the horse shied, thereby drawing upon itself many hard blows from the fierce and haughty rider.

Passing out of the castle-gates, and turning eastward, as he judged, by the position of the sun, the Caliph proceeded in the direction which would enable him, he hoped, in due time, to reach his own country. He had not gone far when he met a rough country fellow who carried a long piece of wood on his shoulder, and Haroun would have been struck full in the face with it had he not stepped quickly on one side to avoid it. But the man, although he passed close by him, neither looked at nor spoke to him, and seemed altogether unconscious of his presence.

It now first dawned upon the Caliph that the strange and invisible substance which he had picked up in the dungeon, and which he still carried in his hand, possessed indeed the marvellous property of rendering him entirely invisible to other men. This accounted for the remarkable panic of his jailer, who, when he looked into, and even entered his dungeon, failed to see him; it explained why the soldiers had permitted him to leave the building unmolested, why the horseman had nearly ridden over him, and why the clown who had just passed had, without knowing it, nearly brained him with his load.

Much comforted and strengthened by the discovery of this wonderful exemption from observation which he now enjoyed, he walked on briskly, till the sun, being now high in the heavens, and the heat very great, he came to a village, and entering boldly an inn there, and passing through into an empty apartment, he lay down upon a not very soft divan he found in it, and straightway fell asleep.