M. Aubanel, who makes but one class of hallucinations and illusions, has proposed the following division: -

1. The hallucinated are fully aware of the phenomena they experience; they attribute it themselves to a freak of fancy, to a diseased imagination; they are perfectly rational, sometimes even manifesting a high development of intellect.

2. The hallucinated cannot understand that their false impressions are received through any other medium than their senses; they are always careful to keep their actions subordinate to the phenomenon which affects them.

3. The hallucinated believe in the interposition of their senses, and in the reality of the external impressions which occur to them. These distinctions apply alone to isolated hallucinations.

In regard to the hallucinations of complex mental alienation, M. Aubanel notices a sensorial monomania, in which "the hallucinated maintain a connected series of ideas, and have none of that disorder or incoherence observable in madmen;" and a sensorial mania, "made up of numerous and various hallucinations, sometimes lucid, more frequently confused, each having the common characteristic of being insanity in itself - that is to say, as incoherent and disordered as are actions and words in the frenzy of madness."

Dr. Paterson, availing himself of the works of Ferriar, Hebbert, Abercrombie and his disciples, commences by dividing hallucinations into two great sections: 1. Those of wakefulness. 2. Those of dreams. He then proposes a new classification, the most complete which has been published in England. It is composed of seven groups, which comprehend the major part of known hallucinations, and one of which admits the existence of hallucinations with reason.*

In common with most of the authors who have preceded him, Mr. Paterson combines hallucinations and illusions.

The classifications of Messrs. Baillarger and Parchappe have already been noticed.

The classification that we are about to introduce exhibits hallucinations in a much more extensive view. We recognize the hallucinations of illusions, although they constantly approximate, because their origin differs entirely; but, after having characterized their distinctions, we shall point out, in describing hallucinations, what is important to be known of illusions, as it is impossible, in many circumstances, that these two forms of mental aberration should be isolated. The same remark applies to idiopathic and symptomatic hallucinations; however useful in a scientific point of view, it cannot be rigorously maintained in a history of hallucinations.

These distinctions established, we shall proceed to divide hallucinations into ten sections, shown in the following table, but which, from the importance of many of them, are also subdivided: -

Section I. Hallucinations consistent with reason.

Section II. Simple hallucinations, in themselves having the characteristic of insanity, without being complicated with monomania, mania, madness, etc.

* Paterson, Me'moires sur plusieurs cas d'hallucinations (Annal. M6-dico-Peychol., 1843). † This subdivision applies to other sections.

Section HI. Hallucinations in their connection with illusions. Section IV. Compound hallucinations, having in themselves the characteristic of insanity, existing,

1. With monomania;

2. With stupidity;

3. With mania;

4. With madness;

5. With imbecility.

Section V. Hallucinations resulting from delirium tremens, intoxication, and narcotic substances, and venoms.

Section VI. Hallucinations most frequent in nervous diseases, but without the accessories of monomania, mania, and madness.

1. With catalepsy;

2. With epilepsy;

3. With hysteria;

4. With hypochondria;

5. With rage.

Section VII. Hallucinations with nightmare and dreams.

Section VIII. Hallucinations with ecstasies.

Section IX. Hallucinations with febrile, inflammatory, and acute diseases, chronic and other affections, with certain states of the atmosphere; namely,

1. With acute diseases;

2. With fever;

3. With diseases of the brain;

4. With parenchymatous inflammations;

5. With typhoid fever;

6. With intermittent fever;

7. With gout, chlorosis, pellagra, etc.;

8. With the last stages of hectic diseases;

9. With syncope, asphyxia, lethargy, convalescence, etc.; 10. With atmospheric influences, etc.

Section X. Epidemic hallucinations.*

As the subdivision we have presented appears to us to comprehend all known hallucinations, it is evident that, when we shall have completed our examination, we shall have all the materials by whose aid we can study their symptoms, their causes, their lesions, their prognosis, their diagnosis, and their treatment. To make choice of the most authentic facts, the most appropriate for establishing the doctrine of hallucinations; to avoid crowding them together, the fault of so many modern authors; to refer to our own experience, whilst we glean from that of the learned both of our own and foreign countries - such are the rules by which we propose to be guided in our researches on a subject which bears relation to medicine, philosophy, history, morals, and religion, and which is, without doubt, the most interesting in mental pathology.

* Epidemic hallucinations and illusions being noticed in the chapters with which they have more particular connection, we shall not devote any special article to them.