Looking for Cannonballs

The System of the World (p. 159) strikes again:

"That is the problem, Dappa: each [letter] refers to a different [story]. It seems that if you put enough stories out before the public, many a reader will find one that speaks to him. But there is no telling which."

"What we've been doing, then, is a bit like firing grapeshot," Dappa mused. "Chances are that a ball will strike home—but there's no telling which—so, best fire a lot of 'em."

"And grapeshot is a useful tactic sometimes," Eliza said, "but it never sank a ship, did it?"

"No, my lady, grapeshot can never do that."

"I say we have now fired enough grapeshot. It has had all the effect it is ever going to have. What we need now, Dappa, is a cannonball."

(emphasis mine)