Glory Road by Robert A. Heinlein

“Milord love, water is heavy. If we try to hang everything on us against any emergency, like the White Knight, we’ll be too weighted down to fight. I’m going to have to strain to usher through three people, weapons, and a minimum of clothing. Living bodies are easiest; I can borrow power from you both. Once-living materials are next; you’ve noticed, I think, that our clothing is wool, our bows of wood, and strings are of gut. Things never living are hardest, steel especially, yet we must have swords and, if we still had firearms, I would strain to the limit to get them through, for now we need them. However, milord Hero, I am simply informing you. You must decide–and I feel sure I can handle, oh, even half a hundredweight more of dead things if necessary. If you will select what your genius tells you.”

“My genius has gone fishing. But, Star my love, there is a simple answer. Take everything.”

“Milord?”

“Jocko set us out with half a ton of food, looks like, and enough wine to float a loan, and a little water. Plus a wide variety of Nevia’s best tools for killing, stabbing, and mayhem. Even armor. And more things. In that foldbox is enough to survive a siege, without eating or drinking anything from Karth-Hokesh. The beauty of it is that it weighs only about fifteen pounds, packed–not the fifty pounds you said you could swing by straining. I’ll strap it on my own back and won’t notice it. It won’t slow me down; it may armor me against a swing at my back. Suits?”

Star’s expression would have fitted a mother whose child has just caught onto the Stork hoax and is wondering how to tackle an awkward subject. “Milord husband, the mass is much too great. I doubt if any witch or warlock could move it unassisted.”

“But folded up?”

“It does not change it, milord; the mass is still there–still more dangerously there. Think of a powerful spring, wound very tight and small, thus storing much energy. It takes enormous power to put a foldbox through a transition in its compacted form, or it explodes.

I recalled a mud volcano that had drenched us and quit arguing. “All right. I’m wrong. But one question–If the mass is there always, why does it weigh so little when folded?”

Star got the same troubled expression. “Your pardon, milord, but we do not share the language–the mathematical language–that would permit me to answer. As yet, I mean; I promise you chance to study if you wish. As a tag, think of it as a tame spacewarp. Or think of the mass being so extremely far away–in a new direction–from the sides of the foldbox that local gravitation hardly matters.”

(I remembered a time when my grandmother had asked me to explain television to her–the guts, not the funny pictures. There are things which cannot be taught in ten easy lessons, nor popularized for the masses; they take years of skull sweat. This be treason in an age when ignorance has come into its own and one man’s opinion is as good as another’s. But there it is. As Star says, the world is what it is–and doesn’t forgive ignorance.)

But I was still curious. “Star, is there any way to tell me why some things go through easier than others? Wood easier than iron, for example?”

She looked rueful. “No, because I don’t know myself. Magic is not science, it is a collection of ways to do things–ways that work but often we don’t know why.”

“Much like engineering. Design by theory, then beef it up anyhow.”

“Yes, milord husband. A magician is a rule-of-thumb engineer.”

“And,” put in Rufo, “a philosopher is a scientist with no thumbs. I’m a philosopher. Best of all professions.”

Star ignored him and got out a sketch block, showed me what she knew of the great tower from which we must steal the Egg of Phoenix. This block appeared to be a big cube of Plexiglas; it looked like it, felt like it, and took thumbprints like it.

But she had a long pointer which sank into it as if the block were air. With its tip she could sketch in three dimensions; it left a thin glowing line whenever she wanted it–a 3-dimensional blackboard.