"I do not understand the particulars in regard to their condition, and hence, am not qualified to offer an opinion. It may be that the disease in them had worked some organic change that was not so easy to overcome, or, it may be that the suggestion that removed the pain put them to sleep. I see they are apparently sleeping soundly."
"I hope their sleep may be a favorable indication," said the Captain. "I do not," he continued, "understand this strange disease which seems to single out the most robust and powerful. Can you explain it to me?"
"The atmosphere of this inner world," interposed Iola, "is highly stimulating, and it requires much active exercise to provide an outlet for the surplus energy that is generated. You were becalmed. Your sailors had nothing to do but to rest when they were not tired. The energy was created and it must be expended. Mental activity would have accomplished this, and their health would have been improved. But failing in this, it took the form of fever and acute pains. The best, in fact, the only efficient safeguard from disease, situated as you were, is to be found in mental activity."
"You certainly do not mean to say that mentally active people are not liable to get sick in this inner world?" remarked the Captain.
"Nothing of the kind," said Iola. "But I will say this, that all other conditions being equal, mentally active people are not in as much danger, provided they think healthy thoughts. If they think disease and fear the worst, they will be even more liable than others to get just what they think. But if the active mind is trained to exercise its power to preserve the health of the body, there is no danger from disease."
"This is a strange doctrine," said the Captain, "and one that I am anxious to know more about, but that must be learned further on, I suppose, as MacNair says."
We had been rising slowly until we had now attained a great height and MacNair interrupted the discussion of mental suggestion by saying:
"We have designedly ascended to a greater height than usual, so as to be above the more humid atmosphere. This will give you a better opportunity to make observations."
"But what observations can we make," I asked, "that could not be made from the surface? When I became satisfied from seeing the sun shining through the southern verge, that we had passed into an inner world, I expected with the telescope, to be able to scan every part of the surface, but I found that I was seemingly as far from being able to do so, as when I was in the outer world. Can you explain to me why I cannot turn my glass to the zenith and see the opposite side of the concave?"
"There can be but one reason," said MacNair, with a merry twinkle in his eyes. "The gaseous contents of the concave must be opaque to your vision."