To Sylvester Schoening
Dear Mr. Schoening, 24 March 1955
Your question is difficult to answer, since Thomistic psychology is on a metaphysical basis, and the psychology of the unconscious on an empirical foundation.
Through many talks with theologians, I have learnt that the greatest difficulty in discussing this matter consists in the difference of the point de depart.
The theologian starts with philosophical concepts which have practically nothing to do with the merely nominalistic concepts of the empiricist.
The theological terms contain what they are giving a name to, the empirical terms are just labels and don't contain what they are naming.
The empirical emphasis is on facts, and names mean very little; also hypotheses mean just as little as they can easily be exchanged for a better point of view.
The only possibility of a discussion I can see is the comparison of certain Thomistic statements with the statements of empirical psychology.
If you have a chance to come to Zurich beginning of May, you will have an opportunity of meeting the Dominican Father Victor White who is delivering a course of lectures at the C. G. Jung Institute.
I have done a number of such comparisons with him, and he has a fair knowledge of my psychology, so that if you have a chance to talk with him it might be of considerable importance to you.
If you should come to Zurich I am ready to see you and talk to you about this subject, but you must keep in mind that my knowledge of Thomistic psychology is almost nil since I have devoted all my available time to the study of facts and not of opinions.
C.G. Jung ~Carl Jung, Letters Vol. II, Pages 234-235