"No, I am a Seventh Order humanoid, an enormous improvement over all the others, since I have what amounts to an endocrine balance created electronically. It is not necessary for me to have a built-in 'no-harm-to-humans' circuit because I can weigh the factors involved far better than any human can.
"You will become aware of the fact that I am superior to you and the rest of your race because I do not need oxygen, I never am ill, I need no sleep, and every experience is indelibly recorded on circuits and instantly available. I am telekinetic, practically omniscient and control my environment to a large extent. I have a great many more senses than you and all are more highly developed. My kind performs no work, but is given to study and the wise use of full-time leisure. You, for example, are comparable to a Fifth Order robot."
"Are there still humans on Zanthar?"
The robot shook his head. "Unfortunately the race died out through the years. The planet is very similar to yours, though."
"But why did they die out?"
The robot gave a mechanical equivalent of a sigh. "When the Seventh Order humanoids started coming through, we were naturally proud of ourselves and wanted to perpetuate and increase our numbers. But the humans were jealous of us, of our superior brains, our immunity to disease, our independence of them, of sleep, of air."
"Who created you?"
"They did. Yet they revolted and, of course, quickly lost the battle with us. In the end they were a race without hope, without ambition. They should have been proud at having created the most perfect machines in existence, but they died of a disease: the frustration of living with a superior, more durable race."
Prof. Tomlin lit a cigaret and inhaled deeply.
"A very nasty habit, Professor Tomlin," the robot said. "When we arrive, you must give up smoking and several other bad habits I see that you have."