" Freud’s theoretical differences with Adler and Jung ended in bitterness. The three parted company and each went his own way. At that point, Freud began to use the concept of introversion as a negative, implying a turning inward away from the world, in his writings about narcissism. This shifted the evolution of the concept of introversion away from healthy and toward the unhealthy, a misconception that remains to this day. "

― Marti Olsen Laney , The Introvert Advantage: How to Thrive in an Extrovert World