“Now, the ticklish part of the job will be to open the Spot just long enough to permit us to get through, yet prevent the whole Prophecy from coming to pass. We've got to get through, together with that black case of mine, and then shut the door in the face of all Thomahlia!”

Nothing more was said on the subject until late the following afternoon, as the doctor, Harry, and Chick sat down to a light meal. They ate much as if nothing whatever was in the wind. From where they sat, in one part of a wing of the temple, they could look out into the crowded streets, in which were packed untold numbers of pilgrims, all pressing towards the great square plaza in front of the temple. No guards were to be seen; the solemnity of the occasion was sufficient to keep order. But the terrific potentiality of that semi-fanatical host did not cause the doctor's voice to change one iota.

“There is no telling what may happen,” he said. “For my own part I shall not venture near the Spot of Life until just at the end. I shall remain in the chamber underneath.

“But you two ought to show yourselves immediately after sundown. Certain ancient writings indicate it. You, and the Nervina, will have to mount the stair to the Spot, and remain in sight until midnight—until the end.

“So we must be prepared for accidents.” He took some papers from his pocket, and selected two, and gave one to each of his pupils. “Here are the details of what must be done. In case only one of us gets through, it will be enough.”

“But—how can these be of any use, on such short notice?” Harry asked.

“Cudgel your brains a bit, gentlemen,” he chided good-humouredly. “You will soon see my drift. This is one of those occasions when the psychic elements involved are such that, without doubt, it were best if you reacted naturally to whatever may happen.

“Now you will note that I have made a drawing of the Blind Spot region; also certain calculations which will explain themselves.

“Moreover, I have written out the combination to my laboratory safe in my house in Berkeley. The green stone is there. Bertha will help, as soon as she understands that it is my wish; no explanation will be needed.

“You may leave the rest to me, young gentlemen. Act as through you had no notion that I was down below the Spot. I shall be merely experimenting a bit with that circle of jewels, to see if the phenomena which affected the Aradna cannot be repeated. I fancy it was not mere accident, but rather the working of a 'period.'”