and abdomen, also from the origin and distribution of the nerves of the cauda equina, that this can be no more than a gross general direction; and that the great number of sympathetic influences from these causes, also from the running of vibrations along membranes, and from their fixing particularly in nervous parts or extreme ones, will give occasion to many deceptions here, and in certain cases make the pain be felt, i.e. appear to be, in parts at a considerable distance from the seat of the disorder.
Fifthly, Suppose the patient to shew by the external parts whereabouts his pain is felt internally, then the physician may, from his knowledge of the situation of the internal parts in respect of the external, guess pretty nearly what internal part is affected.
Sixthly, The symptoms attending the pain, its cause and consequences, compared with the natural functions of the parts, with the history of diseases, and morbid dissections, will enable the physician to determine with great precision in some cases, and help a little in most.
Seventhly, When the patient has had long experience of the same kind of internal pains, or of different ones, he describes more exactly, and also gets certain fixed points, to which he refers his pains.
Eighthly, Anatomists and physicians may sometimes judge with great exactness in their own cases, having both a knowledge of the parts, and their functions, and also their own feelings to guide them.
This subject deserves a particular and accurate examination, it being of great consequence to be able to discover the seat and causa proxima of the distemper, from the complaints of the patient, and from the previous, concomitant, and consequent circumstances. I hope these two propositions may cast some light upon it.
Here we may add an observation deducible from the doctrine of association; viz. As we learn by degrees, from impressions made on the surfaces of our bodies, to attend particularly to the sensations impressed on, or existing in, each part, at pleasure, i.e. to magnify the vibrations which take place in it; so after disorders in the internal parts, the associated circumstances seem often to renew the painful vibrations there, and to occasion either the return of the like disorder, or some other; at least to have a considerable share in these effects, when produced by their causes in an inferior degree. Thus disorders in the bowels, caused at first by acrid impressions, lay the foundation for a return of like disorders on less occasions. Thus women that have often miscarried, seem to irritate the muscular fibres of the uterus by the recollection of the associated circumstances, and so to dispose themselves to miscarry more than according to the mere bodily tendency; fear and concern having also a great
