This is no very new theory; but it has been for Dr. Handheld Jones, by a large number of cases and experiments, as collated in his admirable work on “Functional Nervous Disorders,”[1] to make it “abundantly clear that the great majority of disorders we have to treat at the present time show more or less marked indications of failure of nervous power.” Dr. Jones confines himself “to such disorders as are termed functional;” and I agree with him that “it seems a vain dispute, whether in strict accuracy there are, or are not, any such disorders; ... for it is perfectly certain that there are very grave disorders in which the most careful scrutiny fails to detect any actual change, in which complete recovery is perfectly possible, and in which the ‘juvantia’ are such as to operate more in modifying the power of the organs than the texture.” Dr. Jones then gives two typical cases of functional and organic disease, between which, as he justly observes, “there intervene numerous instances of more or less mixed character;” and adds, that “disease which commences essentially as functional may end as organic.” Footnote 1: London, Churchill, 1864. I am so pleased to be supported by my old friend and colleague in views that I myself have long entertained, that I intend, without further preface, to make his researches the whole substratum of my work; and hope to show how, on the basis of Dr. Jones’s experiments, it is possible to prove the philosophy of my own practice. Whichever of the terms, “inhibitory influence” (Handfield Jones and Lister), “reflex relaxation” (Brinton), or “reflex paralysis” (Brown-Séquard), be used, the fact is ceded by all, that “the energetic operation of an afferent nerve” (Lister), or some impression acting injuriously on an afferent nerve (Handfield Jones), or, again, “an actually existing irritation” (Brown-Séquard), exerts an injurious effect on its nerve centre, this state being, as Dr. Brown-Séquard thinks, increased or diminished according to the activity of the irritation, and ceasing with its entire removal, or, more probably, as Dr. Handfield Jones affirms, persisting after the cessation of the cause which has morbidly affected it. This latter view appears to me the more generally correct one, because it can hardly be expected that a gradual disease will be suddenly removed, there having been no time for recovery of nerve power.