The explanation only brought uproarious merriment from Challenger.  He laughed until everything in the room seemed to rattle and quiver.

“Our worthy Summerlee is, not for the first time, somewhat out of touch with the facts of the situation,” said he at last, mopping his heated brow.  “Now, gentlemen, I cannot make my point better than by detailing to you what I have myself done this morning.  You will the more easily condone any mental aberration upon your own part when you realize that even I have had moments when my balance has been disturbed.  We have had for some years in this household a housekeeper—­one Sarah, with whose second name I have never attempted to burden my memory.  She is a woman of a severe and forbidding aspect, prim and demure in her bearing, very impassive in her nature, and never known within our experience to show signs of any emotion.  As I sat alone at my breakfast—­Mrs. Challenger is in the habit of keeping her room of a morning—­it suddenly entered my head that it would be entertaining and instructive to see whether I could find any limits to this woman’s inperturbability.  I devised a simple but effective experiment.  Having upset a small vase of flowers which stood in the centre of the cloth, I rang the bell and slipped under the table.  She entered and, seeing the room empty, imagined that I had withdrawn to the study.  As I had expected, she approached and leaned over the table to replace the vase.  I had a vision of a cotton stocking and an elastic-sided boot.  Protruding my head, I sank my teeth into the calf of her leg.  The experiment was successful beyond belief.  For some moments she stood paralyzed, staring down at my head.  Then with a shriek she tore herself free and rushed from the room.  I pursued her with some thoughts of an explanation, but she flew down the drive, and some minutes afterwards I was able to pick her out with my field-glasses traveling very rapidly in a south-westerly direction.  I tell you the anecdote for what it is worth.  I drop it into your brains and await its germination.  Is it illuminative?  Has it conveyed anything to your minds?  What do you think of it, Lord John?”

Lord John shook his head gravely.

“You’ll be gettin’ into serious trouble some of these days if you don’t put a brake on,” said he.

“Perhaps you have some observation to make, Summerlee?”

“You should drop all work instantly, Challenger, and take three months in a German watering-place,” said he.

“Profound!  Profound!” cried Challenger.  “Now, my young friend, is it possible that wisdom may come from you where your seniors have so signally failed?”

And it did.  I say it with all modesty, but it did.  Of course, it all seems obvious enough to you who know what occurred, but it was not so very clear when everything was new.  But it came on me suddenly with the full force of absolute conviction.