"The answer," Blackburn said, "is this: the experimental observer, not the one who takes the time trip, must be standing in plain view of the building. He must be expecting gargoyles to appear. When they do, he will not be tempted to call the phenomenon a miracle. When the gargoyles suddenly pop out—in apparent defiance of various physical laws—he can intelligently conclude that a specific time experiment has been performed and that a change in the past has in fact occurred, a conclusion that will restore the appearance of the gargoyles to the realm of non-miraculous events."
"Then the change we make must be so specific, must have such easily deducible consequences, that we'll be able to anticipate our equivalent of the gargoyles."
"Sort of like an either/or proposition," Blackburn said. "Find an event that can go only one of two ways. Switch this event from its already proceeding alternative to the bypassed, the not-used, the temporally-no-longer-existing possibility. The independent observer, watching the one disappear and the other take its place, will then know that the past has changed. It will prove the principle that man can determine his fate and is therefore alone."
Rowan nodded, chewing on his pipe. "I'll wait'll it's over, though," he said.
President Freylinghuysen filled a glass with ice water.
"'You cannot take God's photograph,'" he said. "Surrealism. Sheer surrealism. Was he smiling when he said it?"
"Of course he was smiling," Blackburn replied bleakly. "He's always smiling."
"After making man's first trip through time," Freylinghuysen said, "he stepped out of the physics building to find your either/or proposition yelling its head off and Rowan here standing in the center of Voltaire Mall with half a dress in his hand. So I'm surprised he was smiling. But what was he talking about?"
"And why," Shaheen said, "did he push Blackburn into the shrubbery and run off with the camera? I don't understand that at all." He turned away. "Oh, I suppose there's plenty I don't understand."