An unprecedented history of the personality test conceived a century ago by a mother and her daughter - fiction writers with no formal training in psychology - and how it insinuated itself into our boardrooms, classrooms, and beyond. The Myers-Briggs Type Indicator is the most popular personality test in the world. It has been harnessed by Fortune 100 companies, universities, hospitals, churches, and the military. Its language of extraversion vs. introversion, thinking vs. feeling has inspired online dating platforms and Buzzfeed quizzes alike. And yet despite the test's widespread adoption, experts in the field of psychometric testing, a 500 million industry, struggle to account for its success no less validate its results. How did the Myers-Briggs insinuate itself into our jobs, our relationships, our internet, our lives? First conceived in the 1920s by the mother-daughter team of Katherine Briggs and Isabel Briggs Myers, a pair of aspiring novelists and devoted homemakers, the Myers