514 O F T H E S Y MP A T H Y
of the intercoflals, with the other nerves of the body Nor is it
more furprifing, that an uncommon irritation of any fenfible part
fhould, efpecially in thofe of a delicate frame, produce convulfive
motions of almoft the whole body, through the intervention of the
brain, than that opium applied to the nerves of the ftomach, inte-
ftines, or abdominal mufcles, fhould quickly deftroy the powers
of feeling and motion throughout the whole nervous fyftem f.
17. Nothing makes more fudden or 'more furprifing changes
in the body, than the feveral paffions of the mind. Thefe, howe¬
ver, a<5l folely by the mediation of the brain, and, in a ftrong
light, fliew its fympathy with every part of the fyflem.
Such is the conftitution of the animal frame, that certain ideas
or affeélions excited in the mind are always accompanied with cor-
refponding motions or feelings in the body ; and thefe are owing
to fome change made in the brain and nerves by the mind or fen-
tient principle J : but what that change is, or how it produces thofe
effedls, we know not : as little can we tell, why fhame fhould raife
a heat and rednefs in the face, while fear is attended with a pale-
nefs. Thefe, and many other effe<5ts of the different paffions, muff
be referred to the original conftitution of our frame, or the laws of
union between the foul and body*
But although, in thefe matters, we muff confefs our ignorance,
yet, from what we certainly know of the action of the nerves, we
can eafily fee, that a change in them may occafion many of thofe
effects which are produced by the paffions^
As
# Dr Hillary has remarked in the colica pifionum* that when the pain in the bowels has con¬
tinued long, and at laft begins to abate, a pain in the fhotftder-points, and adjoining mufcles,
comes on, with an unufual fonfation and tingling along the fpinal marrow, that foon extends
itfelf from thence to the nerves of the arms and legs ; which members firft become weak, and
afterwards quite paralytic. Vid. Hillary on the Epidemical difeafes of Barbadoes, p. 184. and
185. Does not this observation feem to Ihew, that the palfy of the extremities, occafioned by
the colica piftonwn, is not owing to any communication between the nerves of the bowels and