me to.
Then, in cases where experts like myself have got up the evidence, the
jury can be made to see through trained eyes."

The Home Secretary tapped impatiently with his foot.

"I can't listen to abstract theorizing," he said. "Have you any fresh
concrete evidence?"

"Sir, everything depends on our getting down to the root of the matter.
What percentage of average evidence should you think is thorough, plain,
simple, unvarnished fact, 'the truth, the whole truth, and nothing but
the truth'?"

"Fifty?" said the Minister, humoring him a little.

"Not five. I say nothing of lapses of memory, of inborn defects of
observational power--though the suspiciously precise recollection of
dates and events possessed by ordinary witnesses in important trials
taking place years after the occurrences involved, is one of the most
amazing things in the curiosities of modern jurisprudence. I defy you,
sir, to tell me what you had for dinner last Monday, or what exactly you
were saying and doing at five o'clock last Tuesday afternoon. Nobody
whose life does not run in mechanical grooves can do anything of the
sort; unless, of course, the facts have been very impressive. But this
by the way. The great obstacle to veracious observation is the element
of prepossession in all vision. Has it ever struck you, sir, that we
never see anyone more than once, if that? The first time we meet a man
we may possibly see him as he is; the second time our vision is colored
and modified by the memory of the first. Do our friends appear to us as
they appear to strangers? Do our rooms, our furniture, our pipes strike
our eye as they would strike the eye of an outsider, looking on them for
the first time? Can a mother see her babe's ugliness, or a lover his
mistress' shortcomings, though they stare everybody else in the face?
Can we see ourselves as others see us? No; habit, prepossession changes
all. The mind is a large factor of every so-called external fact. The
eye sees, sometimes, what it wishes to see, more often what it expects
to see. You follow me, sir?"

The Home Secretary nodded his head less impatiently. He was beginning to
be interested. The hubbub from without broke faintly upon their ears.

"To give you a definite example. Mr. Wimp says that when I burst open
the door of Mr. Constant's room on the morning of December 4th, and saw
that the staple of the bolt had been wrested by the pin from the lintel,
I jumped at once to the conclusio