Conventional measures of mental ability, such as intelligence tests and scholarship, show some of the very highest records belong to INFP and INFJ types, who relegate thinking to last place or next to last. The preference for thinking appears to have far less intellectual effect than the preference for intuition, even in some technical fields, such as scientific research, where its influence was expected to be most important.

The visions of the INFJs tend to concern human welfare, and their contributions are likely to be made independent of a mass movement.

[On Jung's theory of psychological types:] My mother, Katharine C. Briggs, introduced it into our family and made it a part of our lives. She and I waited a long time for someone to devise an instrument that would reflect not only one's preference for extraversion or introversion but one's preferred kind of perception and judgment as well. In the summer of 1942 we undertook to do it ourselves.

Introverted feeling types have a wealth of warmth and enthusiasm, but they may not show it until they know someone well. They wear their warm side inside, like a fur-lined coat.

Whatever the circumstances of your life, the understanding of type can make your perceptions clearer, your judgements sounder, and your life closer to your heart's desire

We cannot safely assume that other people's minds work on the same principles as our own. All too often, others with whom we come in contact do not reason as we reason, or do not value the things we value, or are not interested in what interests us.

Extraverts ... cannot understand life until they have lived it. Introverts ... cannot live life until they understand it.