The reader who wants to pursue the matter further, would do well to
read Havelock Ellis’s _Psychology of Sex_, particularly volume six,
which contains the famous chapter on The Art of Love.
He may also gain much by reading Freud’s _General Introduction to
Psycho-Analysis_.
Finally, if he is interested in going more deeply into the psychology
of Jung, the problems of introvert vs. extravert, and the types, he is
referred to Little Blue Book No. 978 (_The Psychology of Jung_), Little
Blue Book No. 980 (_How I Psycho-Analyzed Myself_) and Little Blue Book
No. 985 (_A Psycho-Analysis of America_).