(39) Professor Jastrow also discusses the case of Laura Bridgman, and he is aided in this by an unpublished manuscript on the subject by Dr. G. S. Stanley, which came into his possession, In this account it is said that 'sight and hearing were as absent from her dreams as they were from the dark and silent world, which alone she knew. The tactual-motor sensations, by which she communicated with her fellow-beings, and through which almost all her intellectual food reached her, also formed the mainstay in her dreams.' It is further said that 'Her sleep seems never undisturbed by dreams again and again she would suddenly and rapidly talk a few words or letters with her fingers'; all the people who enter into her dreams talk with their fingers.' She is reported to have said with regard to her dreams: ' I always forget my dreams very soon'; 'I dream many things, but do not remember what I really dream'; ' I do not dream to talk with mouth - I dream to talk with fingers.'

(40) There is ample evidence in the accounts which we possess regarding these two deaf and blind ladies, that their dreams are not mere echoes, and that they are as largely made up of useless inventions and creations as arc the dreams of those who can see and hear.

(41) Jastrow's research in regard to those who are only blind is interesting and suggestive. As I under-stand the results, they may be thus summarised. If the eye is fully employed in sending impressions to the sight centres of the brain, and so in a certain sense feeding and developing them, and if this begins with the early building up of these centres, and is continued for a certain length of time, then, even though blindness comes on and there is no more .stimulation of the sight centres through the eye, a sort of mental possession of sight may continue. In other words, the sight centres, when well started normally, appear to hold on to something, which has been acquired by use, after all normal stimulation has ceased. The evidence of this seems to be found in dream life.

Persons who have become blind before the age of five do not, in their dreams, meet images which are seemingly derived from sight: in other words, they do not appear to see in their dreams or to have visual hallucinations. They are assumed to be in the position of persons born blind, and in connection with this it is pointed out that the age of five is the earliest age at which we remember ourselves - an opinion which many will refuse to accept as correct, grounding the refusal on personal experience, not always of much value. Persons, on the other hand, who become blind after the age of seven, are said to have dream visions, or what may be called the faculty of seeing in dreams. The age from five to seven is called the critical age. This I think is briefly the outcome of Jastrow's recent research, but, as he points out, he was to some extent anticipated by Heermann in 1838, who reached conclusions almost the same-According to him, persons becoming blind at an age appreciably above seven years may continue to have dream visions for a long time - it may be till death, even though post mortem examination may then show 'degeneration of the optic nerves.' But I think it is commonly held, if total blindness has lasted for twenty years or thereby, though it may have come on after the age of seven, that visual dream hallucinations become few or altogether cease. It has been said broadly that dreams continue to be those of the seeing life, but why the seeing life before the age of five should count for nothing does not seem to have been explained.

(42) It is generally accepted that, in the cases of persons who are blind, or deaf, or both blind and deaf, dreaming of a character which is remembered -vivid dreaming - is less common than in normal persons. This may, perhaps, be true, but it does not apply to all individuals. There arc persons with sight and hearing, who appear to dream less vividly than the blind or deaf - much of the difference, whichever way it goes, depending on the constitutional quality and the culture of the mental powers in the individual.

(43) It is broadly correct that the dreams of those who are both blind and deaf are made up of tactual sensations, but, if an inquirer presses for a multitude of dream stories to be used in illustration, he will certainly find what appear to be exceptions - due probably to imperfections in the narratives.

(44) This short study of dreams appears to me to lead to the following opinions:-

(a) That there is no such thing as dreamless sleep.

(b) That thinking is involuntary - to the extent at least that we cannot cease to think under any order of the will.

(c) That thinking has various characters, these being mainly due to the amount of control and direction exercised over it by the will.

(d) That, in addition, there are different qualities of thinking, depending on the original constitution or the existing state of health of each individual.

(e) That thinking never ceases during life, and is essential to the continuance of life.

(f) That dream-thinking is uncontrolled and undirected by the will, is never coherent and concentrated, is more or less of the same character as thinking in delirium, and constitutes a state of mental disorder, which is not a state of disease.

(g) That thinking, when awake, is always to some extent under control of the will, by which it is directed to a subject and kept there.

(h) That there are many degrees of sleep and wakefulness, and as many degrees of efficiency in the controlling and directing power of the will.

(i) That thinking, like breathing or the beating of the heart, does not cause a sense of weariness, though all three, of course, have a wearing out effect on all the organs concerned.

(j) That the will's inhibiting and directing work brings fatigue and a demand for rest.

(k) That the will finds this rest and refreshment in sleep.

(I) That the frequent occurrence of a state of disordered mind occurring in sleep does not do us harm, but on the contrary does us good.

(m) That both in dream-thin king and delirious-thinking the moral faculty is in abeyance.

(45) In the particular branch of research to which this study belongs, absolute proof can seldom be reached. But absolute proof is often as fully absent from other branches of biological research, though its absence may not be always frankly avowed. To a large extent, indeed, in all such studies we have to be content with showing probability. It is not doubted by any one that in the affairs and conduct of life probability is often a safe guide. In like manner it may often be a safe guide in scientific work, so long as its character is kept in sight and it is not allowed to present itself as certainty. In medicine it is largely accepted as a safe guide. Indeed the value of a well worked out probability is never small. Certainty may never emerge from the study of it But a probability may be so strong as to be properly accepted as a certainty, so far as guidance is concerned when action has to follow, and even in its bearing on the study of related matters.