Now, from both these statements, we find that there may be no signs in the primarily affected organ; which, practically rendered, is nothing more or less than saying that in many cases we must not seek for the primarily affected organ where _the symptoms are_; and this is a great fact: because, although it does not necessarily teach us what we must do, it exposes the broken reed on which so many rely. Now the further point, which, as we would contend, time and labour have supplied, is first this—that what Hunter had mentioned as one feature in the history of the sympathies of different organs, and Abernethy as an occasional or not unfrequent occurrence, is, in disorders of any standing, and with the exception of mechanical injury, _in fact the rule_—the _symptoms_ of disorder being almost _never_ in the primary organ; nay, even organic change (disease) is for the _most part_ first seen in a _secondarily_ affected organ. In regard to primarily affected parts, the skin only excepted, they will be found, in the vast majority of cases, to be one or other of the digestive organs. I will endeavour to render the cause of this intelligible. A minute examination of what happens in a living person, especially if it be extended to some thousands of cases, will soon disclose to the most unlettered person a few instructive facts, showing that Nature has a regular plan of dealing with _all_ injurious influences, which, however _various_ many of the _details_ may be, is in general character exquisitely simple, surprisingly beautiful, and intelligibly conservative; and that the various modes on which she exercises this plan, from the cradle to the grave, are, in _frequency, directly in the order of their conservative tendency_. Let us explain. There is no dearth of illustration; the _facts_ are bewilderingly abundant; the difficulty is which to choose, and how to give them an intelligible _general expression_. Let us take a single case. We know that if a mote gets into the eye, there is irritation, immediately there is flow of blood to the part, a gland pours forth an abundant supply of tears, and the substance is probably washed out. Very well; we say that is intelligible. But suppose you have the vapour of turpentine, or any other irritant, the same thing happens; but still you cannot give quite the same _mechanical_ explanation. Again—substances which affect the mouth, nose, and stomach, will irritate the eye without any contact, and cause a flow of tears. Lastly, you know that affections of the mind will do this, and where even we have no _mechanical_ irritant at all.