On this page I read:
Second, in Psychological Types (1920) he [Jung] wrote about interaction between his types. He wrote about “special charm”, “influence at the level of the subconscious” that have towards each other representatives of complementary types. These complementary types should be both rational, or both irrational, and other criteria should be different (for example, ES – IN, or ET – IF). Alas, this hypothesis was expressed only in brief phrases, Jung did not develop it later.
So Jung had already discovered duality? Anybody has the book (Psychological types)? What exactly did Jung write about this? I think only chapter 10 is online. Thanks.