We have had under observation, however, an adult male with bilateral dislocation and extroversion of the bladder, who efficiently performed the duties of a carrier for many years.
"Manual of Surgery Volume Second: Extremities--Head--Neck. Sixth Edition."
Alexander Miles Alexis Thomson
I think that the job of the teacher is to help each type to a position midway between introversion and extroversion.
"A Dominie in Doubt"
A. S. Neill