"They never told us," he said to the alien. "I don't hold any rancor because of it; they dared not tell us, lest we refuse to become one with them. They were fair, though. Long before we were indoctrinated, long before we'd been allowed to attempt our first Contact, we were told that there were dangers. Not the dangers we had heard about, such as the imminent peril of dying if the host died while we were in Contact. Another danger was implied, one which we could only learn of by actually becoming Learners, and one which--once we had learned of it--would be impossible to escape. "With a little thought along the proper lines, we might almost have guessed it. For every action, there is an equal and opposite reaction. One of Newton's laws, applied in an area he did not even suspect existed. "Oh, we were a brave, adventurous lot, all of us. We would be Learners; no alien mind but we could enter it, and actually become the alien for the period of Contact. Thrills, danger and hairsbreadth escapes would be ours. Ultimate adventurers, they called us. And all along, we were fools." The alien refrained from comment, although Jerry could feel its mind waiting, listening, assimilating. "Contact had a drawback. A basic one which we might have guessed, if we hadn't been going around with stars in our eyes and a delightful feeling of superiority over the men who would never know the interior on any minds but their own. In Contact, just as in sunbathing, there is a delayed reaction, a kickback." "Sunbathing?" thought the alien. Jerry's mind swiftly opened for the alien's inspection his full storehouse of information on the subject. In an instant, the alien apprehended the fate that lay in wait for the careless Space Zoologist-- * * * * * "Sure is warm in here," said Bob, running a finger around inside his sweat-dampened uniform collar. "You have to be careful," said Jana, indicating the quartz panes that formed the ceiling and three walls of the solarium. "The quartz passes ultraviolet, unlike glass. You can pick up a severe burn if you sit out here too long without some sort of protection for your skin." The tech nodded. "The insidious thing about sunburn is that you only turn a little pink as long as you're out in the sunlight. It's when you've gone indoors, or the sun has set, or you put your clothes back on that the red-hot burn begins to show up on your flesh." "It's the light-pressure," said Jana. "As long as there's an influx of ultraviolet, the flesh continues to absorb it without showing much reaction. But as soon as you get away from the rays--the burns show up.... I wonder how Norcriss is making out." IV "You mean, then," said the alien to Jerry, "that all the experiences you undergo in Contact are held back under the surface of your mind, waiting there until you let up on the incoming Contact experiences?"