d
others, that on the first inclining towards sleep, we have been suddenly
awakened with a most violent start; and that this start was generally
preceded by a sort of dream of our falling down a precipice: whence does
this strange motion arise, but from the too sudden relaxation of the
body, which by some mechanism in nature restores itself by as quick and
vigorous an exertion of the contracting power of the muscles? The dream
itself is caused by this relaxation; and it is of too uniform a nature
to be attributed to any other cause. The parts relax too suddenly, which
is in the nature of falling; and this accident of the body induces this
image in the mind. When we are in a confirmed state of health and vigor,
as all changes are then less sudden, and less on the extreme, we can
seldom complain of this disagreeable sensation.

SECTION XVIII.

THE EFFECTS OF BLACKNESS MODERATED.

Though the effects of black be painful originally, we must not think
they always continue so. Custom reconciles us to everything. After we
have been used to the sight of black objects, the terror abates, and the
smoothness and glossiness, or some agreeable accident of bodies so
colored, softens in some measure the horror and sternness of their
original nature; yet the nature of the original impression still
continues. Black will always have something melancholy in it, because
the sensory will always find the change to it from other colors too
violent; or if it occupy the whole compass of the sight, it will then be
darkness; and what was said of darkness will be applicable here. I do
not purpose to go into all that might be said to illustrate this theory
of the effects of light and darkness; neither will I examine all the
different effects produced by the various modifications and mixtures of
these two causes. If the foregoing observations have any foundation in
nature, I conceive them very sufficient to account for all the phenomena
that can arise from all the combinations of black with other colors. To
enter into every particular, or to answer every objection, would be an
endless labor. We have only followed the most leading roads; and we
shall observe the same conduct in our inquiry into the cause of beauty.

SECTION XIX.

THE PHYSICAL CAUSE OF LOVE.

When we have before us such objects as excite love and complacency, the
body is affected, so far as I could observe, much in the following
manner: the head reclines something on one sid