Cleaver had called the thing which had brought him low a "pineapple." Any biologist could have told Cleaver that even on Earth the pineapple is a prolific and dangerous weed, edible only by a happy and irrelevant accident. In Hawaii , as Ruiz-Sanchez remembered, the tropical forest was quite impassable to anyone not wearing heavy boots and tough trousers. Even inside the Dole plantations, the close-packed irrepressible pineapples could tear unprotected legs to ribbons.

The Jesuit turned the suit over. The zipper that Cleaver had jammed, was made of a plastic into the molecule of which bad been incorporated radicals from various terrestrial radio-frequency induction, he felt more in the dark than ever.

They had a completely marvelous radio network, which among other things provided a "live" navigational grid for the whole planet, zeroed on (and here perhaps was the epitome of the Lithian genius for paradox) a tree. Yet they had never produced a standardized vacuum tube, and their atomic theory was not much more sophisticated than Democritus' had been!

These paradoxes, of course, could be explained in part by the things that Lithia lacked. Like any large rotating mass, Lithia had a magnetic field of its own, but a planet which almost entirely lacks iron provides its people with no easy way. to discover magnetism. Radioactivity had been entirely unknown on the surface of Lithia, at least until the Earthmen had arrived, which explained the hazy atomic theory. Like the Greeks, the Lithians had discovered that friction between silk and glass produces one kind of energy or charge, and between silk and amber another; they had gone on from there to van de Graaf generators, electrochemistry, and the static jet — but without suitable metals they were unable to make heavy-duty batteries, or to do more than begin to study electricity in motion.