"If the gargoyles are a product of the past-change," Blackburn put in, anticipating the problem, "how are we going to know it? How are we going to perceive the change? That the question?" "Aren't you going to ask what gargoyles have to do with this?" Pendelton said to Chaplain Rowan. "I don't believe I will," Rowan replied, lighting up his pipe. "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." "What about on the trip," Freylinghuysen offered. "Could something have happened--" "What?" Blackburn replied. "He went back in time exactly one hour. He was to walk to Ethel Chattinger's apartment." ("That fabulous woman," Freylinghuysen murmured.) "All he had to do was spill india ink over one of the two new dresses she'd bought. Apparently, the most trying problem of her recent existence was to decide which of the two to wear to her Spanish coach this morning. But he'd be ruining the dress he'd already seen her wearing an hour later on the Mall."