If asked “What's in a name?” one might fairly answer our knowledge of the thing named. Certainly, the primary meaning of the word seems to imply as much. “There is a petrified philosophy in language,” Professor Max Müller remarks; “and if we examine the most ancient word for name, we find it is nâman in Sanscrit, nomen in Latin, namo in Gothic. This nâman stands for gnâman, which is preserved in the Latin co-gnomen. Nâman, therefore, or name, meant originally that by which we know a thing.” And since we know a thing by its qualities or attributes, it follows that all nouns or names “express originally one out of the many attributes of a thing, and that attribute, whether it be a quality or action, is necessarily a general idea. The fact that every word is originally a predicate, that names, though signs of individual conceptions, are all, without exception, derived from general ideas, is one of the most important discoveries in the science of language.” I have quoted these sentences because it is necessary that we should know exactly what we are about when giving names to morbid mental states, whether they be of disorder or defect. They are meant to express as accurately as may be, our knowledge of those states. Hence it follows that naming is no mere ingenious exercise of the intellect, but a procedure of the greatest practical importance. Our knowledge is not only thus generalised, but also rendered easily applicable to particular instances. A single word may in this way indicate attributes, qualities, or the series of events known as causes and effects. In naming mental disease and defects, this method has been long practised. Thus the ancient term melancholia indicates both the characteristic physiognomy and the then supposed cause of a form of insanity in which there is morbid pain of mind. But the term phrenalgia of Guislain, meaning morbid mind-pain simply as differentiated from neuralgia, or morbid body-pain, is obviously better because it indicates the leading fact, attribute, or quality of the thing to be named. Of course the scientific form of the term differentiates the morbid mind-pain of melancholia from normal or ordinary painful feelings. And while the term indicates correctly the chief condition of a group of mental affections, it implies no theory or false fact, as is implied in the term melancholia. For there are persons who are melancholic who have rather a ruddy than a swarthy complexion; and when swarthiness is associated with morbid mind-pain, it is not always or even generally of bilious origin, but is commonly a melasma, and to be distinguished from an icteric tint. “The spleen” is another of those etiological terms which imply both a painful mental state and its cause, and is equally vague as melancholia. All such etiological names whatever are clearly open to the objection that they can hardly fail to be more or less erroneous since but little is known of the essential causes of many mental diseases; as, for example, of melancholia. There are a few great divisions, however, to which the etiological principle is applicable. Thus mental defects may be classed according as they are primary—that is, due to congenital defects in organization and function; or secondary—that is, consecutive to certain other morbid states occurring in a previously healthy brain. To the class of primary defects belong idiocy, partial or total; to the secondary belong amnesia, or loss of memory, dementia, and moria or folly.