In agreement with my honoured collaborator, Dr. C. E. Long, I have made certain additions to the second edition. It should especially be mentioned that a new chapter upon "The Concept of the Unconscious" has been added. This is a lecture I gave early in 1916 before the Zürich Union for Analytical Psychology. It gives a general orientation of a most important problem in practical analysis, viz. of the relation of the psychological ego to the psychological non-ego. Chapter XIV. has been fundamentally altered, and I have used the opportunity to incorporate an article that should describe the results of more recent researches. In accordance with my usual mode of working, the description is as generalised as possible. My habit in my daily practical work is to confine myself for some time to studying my human material. I then abstract as generalised a formula as possible from the data collected, obtaining from it a point of view and applying it in my practical work, until it has either been confirmed, modified, or else abandoned. If it has been confirmed, I publish it as a general view-point, without giving the empirical material. I only introduce the material amassed in the course of my practice in the form of example or illustration. I therefore beg the reader not to consider the views I present as mere fabrications of my brain. They are, as a matter of fact, the results of extensive experience and ripe reflection. These additions will enable the reader of the second edition to become familiar with the recent views of the Zürich School.