Irving smiled feebly; the other boys were thinking it over with puzzled faces.

“That’s an old quibble,” said Irving. “The alternative for running is not running. Therefore when he’s not running—he’s not running.”

“I don’t see that that explains it,” answered Westby. “That’s just making a statement—but it isn’t logic.”

“He’s not running is the negative of he’s running; he’s not not-running is the negative of he’s not running—”

“Then,” said Westby, “how fast must a dog travel that is not not-running to catch a dog that is not exactly running but only perhaps?”

The boys laughed; Irving retorted, “That’s a problem that you might work out on the blackboard sometime.”

Thereupon Westby became silent, and Irving more than half repented of his speech; he knew that in its reference it had been ill-natured.

He noticed later in the day when he went up to the dormitory that the boys tiptoed about the corridors and conversed in whispers; there was an extravagant air of quiet. When they went down to supper, they tiptoed past Irving’s room in single file, saying in unison, “Sh! Sh! Sh!” They all joined in this procession—from Collingwood to Allison. Irving felt that he had taken Allison’s place as the laughing-stock, the butt of the dormitory.

In the evening they came to bid him good-night—not straggling up as they usually did, but in a delegation, expectant and amused. Westby and Collingwood were in the van when Irving opened his door in response to the knock.

“We didn’t know whether you’d shake hands with two such reprobates or not,” said Westby. “We thought it wasn’t quite safe to come up alone—so we’ve brought a bodyguard.”