275. It has been already observed (9), that authors have differed in their acceptation of the term Digestion - some regarding it as merely denoting that preparatory process which the food undergoes in the stomach; while others have received it in a more extensive latitude, as comprehending the whole of that elaborate and complicated series of actions, by which nature converts bread into blood. We cannot, therefore, be surprised to find that pathologists should as widely have differed in their definition of the disease termed Dyspepsia, or Indigestion. Notwithstanding the distinction which Dr. Philip is disposed to establish between these terms, by considering "Dyspepsia"" as expressing a disease much less varied, and of much less extent, than that which he comprehends under the denomination of "Indigestion," I am still disposed to regard them as synonymous; and when they occur in the following pages, I must beg the reader to receive them with that impression. The term Indigestion is evidently nothing more than a literal English translation of the Greek compound Dyspepsia.

276. I define Indigestion to be a disease, in which one or more of the several processes by which food is converted into blood, are imperfectly or improperly performed, in consequence either of functional aberration, or organic lesion. This definition may, perhaps, be opposed, on the ground of its too comprehensive signification; but I may observe, that however extensive may be the series of symptoms which are thus included under one general head, they will afford, when viewed collectively, sufficient evidence of their relation with the digestive process - although, on a loose and hasty observation, they may not present any general principle of dependency and connexion: if they appear disunited, let the practitioner suspect that he has never viewed them with sufficient reference to that physiological harmony which subsists between the organs in which they arise. Acidity of stomach and urinary depositions are equally indicative of deranged digestion; but the mind that is not acquainted with the relations of the stomach and kidneys, or with the connexion which subsists between the formation of perfect chyle and the discharge of natural urine, will not be disposed to arrange symptoms, so apparently remote in their alliance, under one common head.

There are many sympathies subsisting between different functions, which are not perceptible as long as the general balance of health is preserved: this is remarkably the case with the skin and stomach; but the moment this healthy equilibrium is destroyed, the sympathies become apparent. The physiologist, therefore, without an acquaintance with the body in its morbid states, must remain ignorant of some of the more important circumstances of the animal economy. The same reasoning applies to the study of natural philosophy: the discovery of the existence of an electric fluid could never have been made, had the natural conditions of matter, with regard to this agent, remained unchanged: the basis of all chemical research is founded upon the same principle; decomposition, and the developement of the elements of bodies, are effected by overturning the affinities by which they are naturally combined. These observations are introduced in order to warn the practitioner not to deduce any conclusion against the existence of certain sympathies, on the ground of their not being apparent in a state of health.

In a practical point of view, I consider the classifications of the noso-logist as of very little utility; they have no solid foundation in nature, but are entirely the work of human reason - artificial contrivances, for the purpose of assisting us in the acquirement and retention of knowledge. Such an avowal will sufficiently explain the motive which has induced me to throw off the trammels to which I might have been expected to conform.

277. From the sympathy which the stomach entertains for every part of the living body, its functions may become impeded or perverted from the existence of diseases which originate in organs with which it has no immediate connexion. An affection of the head, or even a disease in the urethra, may create sickness, loss of appetite, or a suspension in the digestive process: but such phenomena are not to be confounded with the primary symptoms of Dyspepsia - they are affections of sympathy or induction, and will require very different treatment. As connected with this opinion, I beg to direct the reader's attention to the first case which I have introduced, in my "Practical Illustrations," at the end of the present volume. In distinguishing between such effects, consists the skill of the practitioner; and it requires a comprehension of mind, a freedom from prejudice, a clearness of judgment, and a patience of minute inquiry, that do not fall to the lot of every member of our profession. I am strongly inclined to think that many physicians of the present day are too apt to accuse the alimentary functions of offences which should be charged on other organs.

It is, perhaps, natural in those who have devoted much time and attention to one particular subject, to fall into an error of this kind; they have a favourite child of their own to support, and they prefer it with the blind partiality of a parent.