"No." Tinker sat down in a large chair. "Let's straighten out something right now, Stahl. Dyall was making the first crude statement of an obvious truth. If we have a pleasant sensation it doesn't matter whether it's caused by a rose or a chemical imitation of a rose or by making a brain imagine a rose—doesn't matter except that the real rose itself is the hardest thing to control. So it can't be as intensely real as its imitations."
"Mr. Tinker, isn't that crucial enough for you?" Mrs. Stahl asked. Her voice was so rich and warmly rounded that Smith stared wonderingly at her, as if trying to fathom an alien tongue.
"Not quite," Tinker shrugged. "Stahl, you're discussing the smallest aspect of the three-part equation, Stimulus + Stimulated Body = Experience. Your poet was saying certain changes in Stimulus would still give a Stimulated Body the same Experience as the original. But the philosophers and cyberneticists, they already suspected something more radical. If the Stimulated Body was properly changed, the same Stimulus could give different Bodies the same Experience. In other words, a properly-arranged process would have the same Experience as the life function for which it was substituted."
"Now then," he went on, "all life reproduces itself, right? Well, they finally figured the most important thing to reproduce was a man's Experience itself, not any particular form of Stimulated Body. Of course we have higher ideals. We want the Stimulated Body to be as nearly like what it was as possible—then we can have the best of all possible worlds."
"Some people," Smith grumbled, "don't get their fair share of that best."
"Anyway I hate all theories," said Mrs. Stahl.
Stahl disregarded them as he stared at his cashbox. "My money," he said ominously, "has been changed!"
The two visitors exchanged nervous glances. "That's not possible," said Tinker.
"It is. Somebody's palmed a real one as a substitute!"
"That's very unfair," Smith protested. "We came here as guests, strangers to you and to each other. We've given you the correct degree of envious admiration and now you show your gratitude for our human reaction by saying we're deranged!"