"A touch! A distinct touch!" cried Holmes. "You are developing
a certain unexpected vein of pawky humour, Watson, against which
I must learn to guard myself. But in calling Moriarty a criminal
you are uttering libel in the eyes of the law--and there lie the
glory and the wonder of it! The greatest schemer of all time,
the organizer of every deviltry, the controlling brain of the
underworld, a brain which might have made or marred the destiny
of nations--that's the man! But so aloof is he from general
suspicion, so immune from criticism, so admirable in his
management and self-effacement, that for those very words that
you have uttered he could hale you to a court and emerge with
your year's pension as a solatium for his wounded character. Is
he not the celebrated author of The Dynamics of an Asteroid, a
book which ascends to such rarefied heights of pure mathematics
that it is said that there was no man in the scientific press
capable of criticizing it? Is this a man to traduce?
Foul-mouthed doctor and slandered professor--such would be your
respective roles! That's genius, Watson. But if I am spared by
lesser men, our day will surely come."

"May I be there to see!" I exclaimed devoutly. "But you were
speaking of this man Porlock."

"Ah, yes--the so-called Porlock is a link in the chain some
little way from its great attachment. Porlock is not quite a
sound link--between ourselves. He is the only flaw in that chain
so far as I have been able to test it."

"But no chain is stronger than its weakest link."