Before naming anything, imagine noticing a flower. Colour, scent, expectation and liking arrive together. We begin with that mixed experience.
One impression becomes stronger than the others. The flower’s bright colour catches your attention. A difference begins to stand out.
Now you notice that impression: “I see it.” Jung calls the centre of this conscious point of view the ego.
Looking more closely, we can ask different questions about the same flower. Separating these activities is what Jung calls differentiation.
What is here? Sensation notices the flower’s colour, texture and scent. We use S for this way of perceiving.
What might this mean or become? Intuition notices possibilities and emerging connections. We use N because I will stand for introversion.
How does it fit together? Thinking identifies the flower and reasons about how it grows. We mark this kind of judgment T.
What matters about it? Feeling evaluates whether the flower is worth caring for or preserving. We mark this judgment of value F.
We now have two questions. How do we perceive: S or N? How do we evaluate: T or F? These give the four functions.
One activity may habitually lead. In this example, intuition comes first. The model calls that leading function the dominant.
The opposite activity is less familiar in this example. With N leading, S occupies the inferior role: a counterweight that may need attention.
A leading perception still needs evaluation. Here, thinking supports intuition. This supporting role is called the auxiliary.
The flower is what you encounter. You are the one encountering it. Jung calls these the object and the subject.
An outward orientation gives more weight to the object and the situation. Jung calls this extraversion, written e after a function letter.
An inward orientation gives more weight to the subject’s inner response. This is introversion, written i. Both orientations occur in everyone.
Jung’s four functions each have an inward and outward form: eight in all. Tap a label to explore the same flower through each.
Now give our distinctions a shape. Put S at one end of a line and N at the other. One choice needs one direction.
Copy that line. In the upper row, add F. In the lower row, add T. We have four pairings, ready to connect.
Join matching endpoints between the rows. The result is a square: four combinations of perception and judgment.
Follow NT. It says intuition and thinking, but not which comes first. N leading T differs from T leading N.
Copy the square again. In one copy, perception leads. In the other, judgment leads. NT becomes N → T or T → N.
Join each corner to its matching copy. We have a cube: four pairings in two orders, making eight arrangements.
Keep perception in the lead. The shaded face contains the four arrangements that share that answer. The other two answers can vary.
Move the same cube into a view with room to unfold. Nothing about its eight arrangements has changed.
Open the judgment-leading lid. It hinges on the T side face, not on the opposite purple base.
Swing the four side faces outward. The open lid moves with its attached side. The squares keep their identities.
The six faces now lie flat as a cross-shaped net. Repeated T → N labels are copies of one corner, separated by the cuts.
Raise the four sides again. Separated copies of the same corner move back towards each other.
Close the lid. The cut copies meet, restoring the same eight corners and twelve edges.
Return to the earlier view. We have eight ordered pairs, but we have not yet given the leading function an inward or outward attitude.
Make an inward-leading copy and an outward-leading copy. N → T becomes Ni → Te in one and Ne → Ti in the other.
Connect each corner to its copy. These new edges reverse both attitudes while keeping the functions and their order fixed.
This is our tesseract: sixteen arrangements connected by thirty-two edges. Each corner records perception, judgment, order and dominant attitude.
Follow Ni → Te. An inner interpretation leads; outward thinking helps evaluate it and put it into practice.
The later MBTI code calls this arrangement INTJ. I names the inward lead; N and T name the functions; J identifies outward judgment, here Te.
Give all sixteen arrangements their four-letter names. The codes name corners; they do not tell us everything about a person.
Hold N fixed. Eight arrangements share intuition. Four lie in each attitude cube, forming two matching square faces.
Join those matching faces. They bound a cubic cell containing eight arrangements, all with N.
Now hold I fixed instead. The purple cell contains the eight inward-leading types. Choose it as the base for opening the tesseract.
Make room to open those eight cells. The tesseract is still closed, and the purple I cell stays our base.
Open the E cell around the square it shares with the T cell. The opposite I cell remains fixed.
Swing the six neighbouring cells away from I. The open E cell moves with its attached neighbour.
Eight cubes now form a three-dimensional net. Repeated ENTP labels mark copies of the same corner, separated by cuts.
Raise the six neighbouring cells. Copies of ENTP move back towards the same four-dimensional corner.
Close the E cell last. Its corners and faces meet their neighbours again, restoring the tesseract.
Return to the familiar view. INTJ is still Ni → Te. Changing the projection has not changed the arrangements.
The later four-function convention completes INTJ as Ni → Te → Fi → Se: dominant, auxiliary, third and inferior.
INTJ and INFJ share Ni in the lead. Their support differs: Te in INTJ, Fe in INFJ.
INTJ leads with Ni and supports it with Te. ENTJ leads with Te and supports it with Ni. The same two forms exchange roles.
Reverse the attitudes: INTJ uses Ni → Te; ENTP uses Ne → Ti. Here they are one edge apart; ENTJ is two away.
Change the rule to letters. INTJ and ENTJ are now one edge apart; ENTP is two away. Same types, different neighbours.
Change F to T: INFP becomes INTP. Ne and Si keep their roles; Fi and Te become Ti and Fe.
INTJ and ESFP differ in all four letters. In the four-function convention, the same forms appear in reverse order.
Following edges, it takes four changes to reach the opposite code. A straight diagonal joins the same endpoints through the centre.
Look along that diagonal. Its opposite endpoints overlap in the drawing, although they remain separate corners.
Eight projected corners form a cube. Four are one letter away from INTJ; four are three letters away.
The six corners two letters away form an octahedron in the same view: two square-based pyramids joined at their bases.
Two cube corners and two octahedron corners lie in one plane. Together they bound a rhombus: a four-sided shape with equal sides.
Twelve rhombi enclose the projected outline. This shape is called a rhombic dodecahedron.
Restore the original connections. All sixteen types and thirty-two one-letter edges are still present, including those meeting the overlapping centre points.
Turn away from the exact diagonal. The two central types separate. What looked like one point was two points seen along one line.
Return to the tesseract. The selected INTJ corner holds four roles: Ni leads, Te supports, Fi is third and Se inferior.
Se is inferior in INTJ, but dominant in ESFP and ESTP. The same function takes a different place in each arrangement.
Within INTJ, Fi asks what matters and Te asks what works. Personal value and practical action need to answer to each other.
The tesseract brings sixteen arrangements into one whole. Choose a type, turn the figure, and trace its relations.