ertain as I am of the
alternation of day and night, that there exists close to me an
invisible being that lives on milk and on water, which can touch
objects, take them and change their places; which is, consequently,
endowed with a material nature, although it is imperceptible to our
senses, and which lives as I do, under my roof....

_August 7th_. I slept tranquilly. He drank the water out of my
decanter, but did not disturb my sleep.

I ask myself whether I am mad. As I was walking just now in the sun by
the riverside, doubts as to my own sanity arose in me; not vague doubts
such as I have had hitherto, but precise and absolute doubts. I have
seen mad people, and I have known some who have been quite intelligent,
lucid, even clear-sighted in every concern of life, except on one
point. They spoke clearly, readily, profoundly on everything, when
suddenly their thoughts struck upon the breakers of their madness and
broke to pieces there, and were dispersed and foundered in that furious
and terrible sea, full of bounding waves, fogs and squalls, which is
called _madness_.

I certainly should think that I was mad, absolutely mad, if I were not
conscious, did not perfectly know my state, if I did fathom it by
analyzing it with the most complete lucidity. I should, in fact, be a
reasonable man who was laboring under a hallucination. Some unknown
disturbance must have been excited in my brain, one of those
disturbances which physiologists of the present day try to note and to
fix precisely, and that disturbance must have caused a profound gulf in
my mind and in the order and logic of my ideas. Similar phenomena occur
in the dreams which lead us through the most unlikely phantasmagoria,
without causing us any surprise, because our verifying apparatus and
our sense of control has gone to sleep, while our imaginative faculty
wakes and works. Is it not possible that one of the imperceptible keys
of the cerebral finger-board has been paralyzed in me? Some men lose
the recollection of proper names, or of verbs or of numbers or merely
of dates, in consequence of an accident. The localization of all the
particles of thought has been proved nowadays; what then would there be
surprising in the fact that my faculty of controlling the unreality of
certain hallucinations should be destroyed for the time being!

I thought of all this as I walked by the side of the water. The sun was
shining brightly on the river and made earth delight