There is, finally, the _introspective_ method. This may be said to be the earliest of the more scientific methods of studying dreams. Maine de Biran was here a pioneer, and Maury, in his famous book, _Le Sommeil et les Rêves_ (1861), which inaugurated the modern study of dreams, adopted a mainly introspective method, though he was not always quite successful in avoiding the fallacies of that method. It is in France that this method has been most frequently and most successfully cultivated.
Professor Sigmund Freud's _Die Traumdeutung_ (first edition, 1900), may be said to belong to the introspective class, though to a special division which Freud himself terms psycho-analytic. This is undoubtedly the most original, the most daring, the most challenging of recent books on dreams, and is now the text-book of a whole school of investigators. It is not a book to be neglected, for it is written by one of the profoundest of living investigators into the obscure depths of the human soul. Even if one rejects Freud's methods as unsatisfactory and his facts as unproved, the work of one so bold and so sincere cannot fail to be helpful and stimulating in the highest degree. If it is not the truth it will at least help us to reach the truth.
The little book now presented to the reader belongs mainly to the introspective group of dream studies, though not to the psycho-analytic variety. It is based on data which have accumulated beneath my hands during more than twenty years, and some of the ideas developed in it were put forward in a paper 'On Dreaming of the Dead,' _Psychological Review_, Sept. 1895; in 'A Note on Hypnagogic Paramnesia,' _Mind_, No. 22, 1896; and in 'The Stuff that Dreams are made of,' _Popular Science Monthly_, April 1899. The book is not the outcome of experiment or of any deliberate concentration of thought on dreaming. I have simply noted down dream experiences,--most often in myself, less often in immediate friends,--directly they have occurred, usually on awakening in the morning. The few unimportant exceptions to the rule are duly noted. By maintaining this rule I have been able to satisfy myself that everything I have set down is reasonably accurate. Such a method certainly tends towards the exclusion of peculiar and exceptional dreams. This I do not greatly regret. I am chiefly interested in the problems of normal dreaming; they are sufficiently puzzling and mysterious and they properly present themselves for explanation first. I do not wish it to be understood that I question the existence of telepathic and other abnormal dream experiences. That is not the case. But it so happens that under the conditions I have laid down I have not met with any dreams that clearly and decisively belong to this abnormal class. Such few possible examples as have come under my immediate observation (in no case as personal experiences) are slight, and, moreover, sometimes of too intimate a character for full exposition.