Before entering on the subject, I will summarise the principal facts relating to this question to be found scattered through the works of various authors. I divide them into four groups:—
1. We may take taste and smell together. This last sense is much more extensive, much richer and more varied than the other; common speech often confounds them, enriching taste at the expense of smell. Although unscientific, this confusion does not greatly concern us.
Every one knows that professional tasters, cooks, certain chemists and perfumers, can distinguish the most delicate gradations and correctly identify them with previous sensations; but this is a provoked recollection. Does a spontaneous or voluntary relation exist between these two groups of images? Examining the fullest monographs drawn up by physiologists[[97]] we find scarcely any information on this point. Cloquet, Müller, Valentin have reported cases of subjective sensations attributed by them to internal causes; but other physiologists, such as Ludwig, without denying these, are of opinion that sapid particles in the mouth, and odoriferous molecules on the mucous membrane of the nose, may act in a similar manner; so that the alleged images would, in fact, be sensations.
Dreams may afford us a better starting-point. Among the numerous writers who have treated of this subject, some resolutely deny the existence of representations of taste and smell. It is impossible to accept this opinion. Though they are comparatively rare, examples may be found which are proof against all criticism. A person who, for hygienic reasons, has abstained from wine for several years, assures us that he has had a very clear impression of its taste in the course of a dream. We may recall the hypnagogic hallucinations so well described by A. Maury, who was subject to them; he mentions the taste of rancid oil, and the smell of burning as occurring apart from any objective cause.
Among hallucinations properly so called, it is known that those of smell are of very frequent occurrence. Many authorities hesitate to admit those of taste, which they reduce to the status of mere illusions; but we know that the distinction formerly maintained between these two pathological manifestations has been, in our day, much disputed.
2. Internal sensations play a prominent part in the emotional life. Are these susceptible, in the normal condition, of spontaneous or voluntary revival? I have not been able to find any precise information on this point. In the pathological condition we can find numerous examples in hypochondriacs, hysterics, and neuropaths, in insane patients who complain of the suppression of some of their organs, of inversion of the stomach. In any case it would be necessary to determine the part played by the organ itself, and its actual state in the majority of these cases of revival, which is extremely difficult.
3. As for pleasures and pains, under their double (physical and mental) form, there is no doubt. The recollection of a blinding light, of a discord or a strident sound, of the extraction of a tooth, or some more serious operation; the prospect of a good dinner to an epicure, of the approaching holidays to a schoolboy—all the states of psychic life generally included under the designation of imaginary pleasures and pains, show how frequent is the revival of impressions on the feelings. And, in fact, the difficulty is not to establish their existence, but to determine their nature.
We may also recall the facility with which, in hypnotised subjects, pleasant or painful conditions of all sorts may be induced by suggestion.
Finally, in certain cases, the impression may even become completely hallucinatory—i.e., equal in intensity to the reality itself. “A student,” says Gratiolet, “playfully struck his companion’s out-stretched finger with the handle of a scalpel. The latter felt a pain so acute that he thought the instrument had pierced his finger to the bone.” During a popular tumult in the reign of Louis-Philippe, a combatant received a slight contusion from a spent bullet on his shoulder. The skin was not even scratched, but “he felt a torrent of blood flowing from the wound over his breast.” Bennett relates that a butcher remained hanging by one arm from a hook. He was taken down by the terrified bystanders, uttered frightful cries, and complained that he was suffering cruelly, while all the time the hook had only penetrated his clothes, and the arm was uninjured.[[98]] This condition might be termed a hallucination of the feelings.
4. The supply of observations and documents relating to the revivability of the emotions and passions is a very scanty one. In fact, we may admit that what has already been said as to pleasures and pains is also applicable to this last group. But it is not on the question of fact that the attention of psychologists has been concentrated. They are occupied entirely with theory, and in determining the nature of emotional memory. The majority consider the recollection to be merely that of the accompanying circumstances of emotion. Others hold it to be a recollection of the emotion itself, as such. As this is the principal point of my subject, and will have subsequently to be discussed in detail, I must limit myself, for the moment, to the mere indication of the two opinions.