as of the change in the balance
of personal forces in a human group, is indefinable and beyond proof.
Yet it is unmistakable. And I knew perfectly well at what given moment
the atmosphere within these four walls became charged with the presence
of other living beings besides ourselves. And, on reflection, I am
convinced that both my companions knew it too.

"Watch the light," said the doctor under his breath, and then I knew too
that it was no fancy of my own that had turned the air darker, and the
way he turned to examine the face of our host sent an electric thrill of
wonder and expectancy shivering along every nerve in my body.

Yet it was no kind of terror that I experienced, but rather a sort of
mental dizziness, and a sensation as of being suspended in some remote
and dreadful altitude where things might happen, indeed were about to
happen, that had never before happened within the ken of man. Horror may
have formed an ingredient, but it was not chiefly horror, and in no
sense ghostly horror.

Uncommon thoughts kept beating on my brain like tiny hammers, soft yet
persistent, seeking admission; their unbidden tide began to wash along
the far fringes of my mind, the currents of unwonted sensations to rise
over the remote frontiers of my consciousness. I was aware of thoughts,
and the fantasies of thoughts, that I never knew before existed.
Portions of my being stirred that had never stirred before, and things
ancient and inexplicable rose to the surface and beckoned me to follow.
I felt as though I were about to fly off, at some immense tangent, into
an outer space hitherto unknown even in dreams. And so singular was the
result produced upon me that I was uncommonly glad to anchor my mind, as
well as my eyes, upon the masterful personality of the doctor at my
side, for there, I realised, I could draw always upon the forces of
sanity and safety.

With a vigorous effort of will I returned to the scene before me, and
tried to focus my attention, with steadier thoughts, upon the table, and
upon the silent figures seated round it. And then I saw that certain
changes had come about in the place where we sat.

The patches of moonlight on the floor, I noted, had become curiously
shaded; the faces of my companions opposite were not so clearly visible
as before; and the forehead and cheeks of Colonel Wragge were glistening
with perspiration. I realised further, that an extraordinary change had
come about in the temperat