Well, it sounded simple enough; but I am no hypnotist, and naturally I had considerable doubt as to my ability along these lines.

When I explained this to Umka, he growled impatiently.

"You can never succeed," he said, "if you harbor such doubts. Put them aside. Believe that you will succeed, and you will have a very much greater chance for success."

"But how can I hope to accomplish anything when I cannot see them?" I asked.

"And even if I could see them, aside from a brief moment that the door is open when food is brought us, I have no opportunity to see them."

"That is not necessary," he replied. "You think of your friends, do you not, although you cannot see them now?"

"Yes, of course, I think of them; but what has that to do with it?"

"It merely shows that your thoughts can travel anywhere. Direct your thoughts, therefore, upon these Tarids. You know that the castle is full of them, because I have told you so. Just direct your mind upon the minds of all the inhabitants of the castle, and your thoughts will reach them all even though they may not be cognizant of it."

"Well, here goes," I said; "wish me luck."

"It may take some time," he explained. "It was a long time after I learned the secret before I could pierce their invisibility."

I set my mind at once upon the task before me, and kept it there when it was not otherwise occupied; but Umka was a loquacious creature; and having long been denied an opportunity for speech, he was now making up for lost time.

He asked me many questions about myself and the land from which I came, and seemed surprised to think that there were living creatures upon the great world that he saw floating in the night sky.

He told me that his people, the Masenas, lived in the forest in houses built high among the trees. They were not a numerous people, and so they sought districts far from the other inhabitants of Thuria.

The Tarids, he said, had once, been a powerful people; but they had been overcome in war by another nation and almost exterminated.

Their enemies still hunted them down, and there would long since have been none of them left had not one of their wisest men developed among them the hypnotic power which made it possible for them to seemingly render themselves invisible to their enemies.

"All that remain of the Tarids," said Umka, "live here in this castle. There are about a thousand of them altogether, men, women, and children.

"Hiding here, in this remote part of the world, in an effort to escape their enemies, they feel that all other creatures are their foes. Whoever comes to the castle of the Tarids is an enemy to be destroyed."

"They will destroy us, you think?" I asked.

"Certainly," he replied.

"But when, and how?" I demanded.

"They are governed by some strange belief," explained Umka; "I do not understand it, but every important act in their lives is regulated by it. They say that they are guided by the sun and the moon and the stars.