and the Pirates of the Asteroids as the villains of the series, they remained nothing more than a vague external menace until this particular book. Dr. Peverale describes them thus in chapter 5: "The planets of Sirius are thinly populated and they are extremely decentralized. They live in isolated individual family units, each with its own energy source and services. Each has its group of mechanical slaves — there's no other word possible — slaves in the form of positronic robots, which do the labor. The Sirian humans maintain themselves as a fighting aristocracy. Every one of them can handle a space-cruiser. They'll never rest until they can destroy the Earth . . . . "They despise us. They consider us scarcely more than animals. The Sirians themselves are very race-conscious. Since Earthmen first colonized Sirius, they have been breeding themselves carefully until they are free of diseases and of various characteristics which they consider undesirable. "They are of uniform appearance, while Earthmen are of all shapes, sizes, colors, varieties. The Sirians consider us inferior. That's why they won't let us emigrate to Sirius". The Sirians therefore resemble the 'Solarians' of The Naked Sun, albeit less isolated and far more war-like. In Big Sun of Mercury, Starr notes that "if the Sirians are race-conscious and are breeding themselves into uniformity, they will defeat themselves in the long run. It is variety in the human race that brings about progress. It is Earth and not Sirius that is in the forefront of scientific research. Earthmen settled Sirius in the first place, and it is we, not our Sirian cousins, who are advancing in new directions every year". Also noteworthy is the fact that in Big Sun of Mercury, with its references to positronic robots and the Three Laws of Robotics, Asimov no longer attempts to disguise that he was the true author, although for the sake of continuity, the novel still appeared under his pseudonym of Paul French. External links Science fiction novels by Isaac Asimov 1956 American novels Novels set on Mercury (planet) American science fiction novels Works published under a pseudonym Doubleday (publisher) books