Wheras there was a space of nine years between the first and second editions of this book, the need of a third edition was apparent when little
more than a year had elapsed. I ought to be gratified by this change; but if I was unwilling previously to attribute the neglect of my work to its
small value, I cannot take the interest which is now making its appearance as proof of its quality.
The advance of scientific knowledge has not left The Interpretation of Dreams untouched. When I wrote this book in 1899 there was as yet no
"sexual theory," and the analysis of the more complicated forms of the psychoneuroses was still in its infancy. The interpretation of dreams was
intended as an expedient to facilitate the psychological analysis of the neuroses; but since then a profounder understanding of the neuroses has
contributed towards the comprehension of the dream. The doctrine of dream-interpretation itself has evolved in a direction which was
insufficiently emphasized in the first edition of this book. From my own experience, and the works of Stekel and other writers, [1] I have since
learned to appreciate more accurately the significance of symbolism in dreams (or rather, in unconscious thought). In the course of years, a mass
of data has accumulated which demands consideration. I have endeavored to deal with these innovations by interpolations in the text and
footnotes. If these additions do not always quite adjust themselves to the framework of the treatise, or if the earlier text does not everywhere come
up to the standard of our present knowledge, I must beg indulgence for this deficiency, since it is only the result and indication of the increasingly
rapid advance of our science. I will even venture to predict the directions in which further editions of this book - should there be a demand for
them - may diverge from previous editions. Dream-interpretation must seek a closer union with the rich material of poetry, myth, and popular
idiom, and it must deal more faithfully than has hitherto been possible with the relations of dreams to the neuroses and to mental derangement.
Herr Otto Rank has afforded me valuable assistance in the selection of supplementary examples, and has revised the proofs of this edition. I have
to thank him and many other colleagues for their contributions and corrections.