About a year later Nirgal and the other children began to figure out how to deal with the days when they were taught by Sax. He would start at the blackboard, sounding like a particularly characterless Al, and behind his back they would roll their eyes and make faces as he droned on about partial pressures or infrared rays. Then one of them would see an opening and begin the game. He was helpless before it. He would say something like, “In nonshivering thermogenesis the body produces heat using futile cycles,” and one of them would raise a hand and say, “But why, Sax?” and everyone would stare hard at their lectern and not look at each other, while Sax would frown as if this had never happened before, and say, “Well, it creates heat without using as much energy as shivering does. The muscle proteins contract, but instead of grabbing they just slide over each other, and that creates the heat.”

Jackie, so sincerely the whole class nearly lost it: “But how?”

He was blinking now, so fast they almost exploded watching him. “Well, the amino acids in the proteins have broken covalent bonds, and the breaks release what is called bond dissociation energy.”

“But why?”

Blinking ever harder: “Well, that’s just a matter of physics.” He diagrammed vigorously on the blackboard: “Covalent bonds are formed when two atomic orbitals merge to form a single bond orbital, occupied by electrons from both atoms. Breaking the bond releases thirty to a hundred kcals of stored energy.”

Several of them asked, in chorus, “But why?”

This got him into subatomic physics, where the chain of whys and becauses could go on for a half hour without him ever once saying something they could understand. Finally they would sense they were near the end game. “But why?”

“Well,” going cross-eyed as he tried to backtrack, “atoms want to get to their stable number of electrons, and they’ll share electrons when they have to.”

“But why?”

Now he was looking trapped. “That’s just the way atoms bond. One of the ways.”

“But WHY?”

A shrug. “That’s how the atomic force works. That’s how things came out—”

And they all would shout, “in the Big Bang.”