It is an adventure novel. Before the first ship from Earth made a landing on Venus, there was much speculation about what might be found beneath the cloud layers obscuring that planet's surface from the eyes of all observers. One school of thought maintained that the surface of Venus was a jungle, rank with hot-house moisture, crawling with writhing fauna and man-eating flowers. Another group contended hotly that Venus was an arid desert of wind-carved sandstone, dry and cruel, whipping dust into clouds that sunlight could never penetrate. Others prognosticated an ocean planet with little or no solid ground at all, populated by enormous serpents waiting to greet the first Earthlings with jaws agape. But nobody knew, of course. Venus was the planet of mystery. When the first Earth ship finally landed there, all they found was a great quantity of mud. There was enough mud on Venus to go all the way around twice, with some left over. It was warm, wet, soggy mud—clinging and tenacious. In some places it was gray, and in other places it was black. Elsewhere it was found to be varying shades of brown, yellow, green, blue and purple. But just the same, it was still mud. The sparse Venusian vegetation grew up out of it; the small Venusian natives lived down in it; the steam rose from it and the rain fell on it, and that, it seemed, was that. The planet of mystery was no longer mysterious. It was just messy. People didn't talk about it any more.