"Imagine packing an amount of flammable material in a metal box, then lighting it. Then imagine making such a device that its ignition can happen at a delay. Rather than burn, the fire blows out the sides of the box in pieces, at high speed."

That was Simon's basic understanding of a bomb.

"It is a different sort of horrible than swords and bows," he said grimly. "War is a terrible thing, no matter the tools. There is a reason I sought to be a scholar rather than a knight."