The numbers in parentheses refer to traits in Sheldon's Scale of Temperament and the page number to his Varieties of Temperament.

The endotonic is an extravert. He loves to have people around, a trait Sheldon called sociophilia (8). He is dependent on them for affection and approval (10). The endotonic does not hold back his emotions; whatever is there flows readily and smoothly out (17) and can be easily understood. He wants to be around people when he is troubled (19). He is well-oriented to the social world around him and knows what the general opinion of the community is about many individuals in it (11).

The endotonic has sensation as his first function. He is oriented to the world around him through his sense impressions. "Endotonics can always be trusted to maintain a close grip on immediate practical reality." (p. 249-50). "Endotonia means realism. Endotonic ecstasy lies in the achievement of a 'real' surrounding made up of nice things that taste good, smell good, look good, sound good, feel good." (p. 253). He loves to eat (4) and to be physically comfortable (2), and he likes people simply because they are with him without making judgments about them (9). They are facts which he accepts (13).

The mesotonic is an extravert, with relatively little grasp of his inner self (17). His is an extraversion of action. He loves physical adventure (2) and is full of energy to be doing things (3). He is physically courageous for combat (8) and has an unrestrained voice (13). He dislikes being enclosed in small places (11).

The first function of the mesotonic is thinking. The mesotonic knows what he wants and he has a "singularly impersonal objectivity in seeking what is wanted" (p. 55). He is effective in carrying out decisions without inhibitions. He is stable, predictable and hardheaded (p. 58). He gets things done without always stopping and considering the physical and social costs (p. 59). "The even regulation of habitual overt behavior in mesotonics is striking, but it is perhaps relatively unimportant in comparison with the same habitual ordering of mental activities" (p. 265). This habitual ordering of the mental activities is a result of the predominance of the thinking function.

The ectotonic is an introvert. "The thing to be saved and protected at all costs is the continuity and the integrity of the inner awareness. Such a person disassociates the outer objective reality but remains in the closest touch with his own inward subjective reality."(p. 88) The ectotonic loves privacy (4), tends to avoid much socializing (8) and is restrained both in voice (9) and in the expression of emotions (6).

The most developed function of the ectotonic is intuition. He has a great deal of curiosity and moves from one new interest to another. "He seems to be able to change his mind abruptly and suddenly adapt all his feelings and attitudes to the new orientation." (p. 82) He is oriented to the future (20) and wants to understand the riddles of life (p. 93). "One of the most striking characteristics of persons showing the C-17 trait (introversion) predominantly is their acuity and preciseness of intuition. Intuition is of the first order in these people, for it is based on a thorough familiarity with the remote consciousness from which it springs." (p. 89)

The least developed function is sensation. He cannot seem to accept physical realities matter-of-factly. He has difficulty in forming routines and habits (10) and difficulty in learning things by rote. He either ignores things or reads too much into them. "Ectotonics desire but little, but they seem to become inordinately attached to what they have both in the sense of material goods and in the sense of personal loyalties." (p. 37) Physical objects become alive to them. "He becomes affectionately attached to things, reads human qualities and feelings into them and often focuses deep affection upon things that are not human." (P. 255) He can have an especially difficult time dealing with sexuality. "The ectotonic is always in danger of flying too far from the earth and suffering an Icarian fall" (p. 250).

Sheldon's body type diagram now looks like this:

extraverted thinking extraverted sensation

introverted intuition

But what were the physiques of the other psychological types? Finding out was a harder task. Reading Jung or Sheldon couldn't provide an answer. It had to come from someone who actually left certain body/temperament and psychological tracks. We were already familiar with the ectomorph who was an introverted intuition type. But what about a man we knew who we were sure was an introverted thinking intuition type? He was more mesomorphic and less ectomorphic than the ectomorphs who were introverted intuition types. He was built trimly like a marathon runner. He was what Sheldon would call a 2-4-4, which meant that he was equally mesomorphic and ectomorphic with little endomorphy. Once we had him as a good first example we took a careful look at some other introverted thinking intuition types, and found that they had similar builds.

Then there was a friend who was our favorite example of a zany and exciting extraverted intuition type. He was more muscular than the introverted thinking type, but he still had a good deal of ectomorphy. I think Sheldon would have rated him around a 2-5-4.

The endomorphic mesomorphs who are one of the most popular American somatotypes turned out to be either extraverted sensation types if they were a bit more endomorphic, or extraverted thinking sensation types if they were somewhat more mesomorphic. The body type diagram now looked like this:

This left the introverted sensation type, the introverted thinking sensation type and the question of women. Eventually we placed the introverted sensation type between the endomorph and the ectomorph, and the introverted thinking sensation type became a good example of how type theory has to flow from type practice. It would have been convenient to put the introverted thinking sensation type with the introverted thinking intuition type, but we found an introverted thinking sensation type whose body did not seem to fit this pattern. It was more chunky and less ectomorphic. Then we found several other introverted thinking sensation types who had similar physiques. They still remain a puzzle. Here, however, is how our body type diagram finally looks:

Women follow the same pattern as men but they are more difficult to somatotype, for they are more endomorphic and more closely grouped together. This means there are less women who are extreme mesomorphs and more women who are well-endowed with endomorphy. Women, for example, who are introverted intuition types will have in general more endomorphy than their male introverted intuition counterparts. Women are more naturally midrange and more grouped in the center of the body type diagram. So a relatively small difference in somatotype can be the sign of a large difference in psychological type. Instead of the mesomorph being an extraverted thinking type she is usually an extraverted feeling type, and the introverted thinking intuition types and introverted thinking sensation types become introverted feeling intuition types and introverted feeling sensation types. In short, to convert the above diagram from men to women replace thinking with feeling.

All this sounds a bit complicated, but if we study these diagrams there is a certain interior logic in them. Let's imagine that each of the three corners is like a magnet, and each of these magnetic poles has its strongest influence on the area that is closest to it, while its power of attraction weakens with distance. The ectomorphic pole is associated with introversion and intuition, the mesomorphic pole with extraversion, thinking and feeling, and the endomorphic pole with extraversion and sensation. If we stand on the ectomorphic pole and look towards the mesomorphic one, we see that intuition and introversion grow less strong as we move towards the mesomorphic pole of extraversion, thinking and feeling. The introverted intuition type becomes the introverted thinking or feeling intuition type, then the extraverted intuition type and finally the extraverted thinking or feeling type.

We have already seen Sheldon's description of the body types and temperaments that correspond with the extraverted sensation type, the extraverted thinking type and the introverted intuition type. The thing to note is that while Sheldon was describing the extremes of each somatotype, the territory of each psychological type covers a wide area made up of many somatotypes and temperaments. We should not expect the introverted intuition type to always resemble a bean pole or the extraverted sensation type to look like Santa Claus.

The introverted intuition type covers a wide range of physiques from the walking stick to the slim muscularity of the mesomorphic ectomorph to the midrange balanced body types. In the same way the temperament varies and no doubt the psychological type itself within the territory of the introverted intuition type.

The extraverted sensation type ranges from the roundness of the polar extreme to the burliness of the endomorphic mesomorph who might actually have more mesomorphy than endomorphy and he, too, shares in the midrange balanced somatotypes, who at first glance seem almost the same as the midrange physiques that belong to other psychological types.

The introverted sensation type shows a special type of ectotonic behavior due to his introverted sensation. He has a love of privacy and is restrained in voice and in the expression of his emotions. He does not have the easy extraversion of affect of his neighbor the extraverted sensation type. His emotions, while strong, are held in and shyly bestowed. He does not exhibit the quick friendliness, tolerance and indiscriminate amiability found in the extraverted sensation type. He can set a good table but does not make the same social sacrament out of eating.

The ectotonia of the introverted sensation type takes on a different character because sensation replaces intuition. The introverted sensation type is more orderly and meticulous with details and observant of routines. Their houses are often particularly neat and clean in marked contrast with the introverted intuition type who sins by omission and inadvertence, and the extraverted sensation type who fails by lack of organization. They show none of the quick curiosity and reaction and movement from one topic to another characteristic of the ectotonic introverted intuition type.

The extraverted intuition type shares the extraversion of action of the more mesotonic extraverted thinking type. There is a love of physical adventure and an enjoyment in being out and doing things. He is outgoing and physically courageous but without the same aggressiveness and love of domination that marks the more extreme mesotonic. Neither does he share the mesotonic's knack of rubbing people's feelings the wrong way. He is quick in movement and accident-prone, and his tolerance for pain is mixed with a certain amount of concern for his health. Instead of being youth-oriented he is future-oriented.

He shares the ectotonic's intuition, but not his introversion. He looks to the future outside, changes activities quickly and resists habit and routine. He chafes under authority and loves freedom and independence.

It appears that these types cover two distinct territories; one next to the introverted intuition type, which has the introverted thinking intuition type and the introverted feeling intuition type, and another on the other side which contains the introverted thinking sensation type and the introverted feeling sensation type. Since this is the only instance where a type territory is split up there is a chance that we are mistaking a portly 4-4-4 introverted thinking sensation type for a more endomorphic and/or mesomorphic physique which would place the introverted thinking sensation type and the introverted feeling sensation type on the other side. It is striking, however, that all the types with sensation in the first or second place fall on the left side of the diagram and the introverted thinking sensation type and the introverted feeling sensation type fit into this pattern, so we will describe these types as living in two separate territories.

The introverted thinking intuition type and the introverted feeling intuition type share many of the traits of the ectotonic introverted intuition type with whom they share their introversion and to a lesser degree their intuition, such as love of privacy, emotional restraint, as well as a reluctance to socialize. In a lesser degree they share the quick reactions of the more extreme ectotonics and what Sheldon calls mental over-intensity or hyperattentionality. The introverted thinking intuition type, because of the placement of the thinking function, has what could be called an introverted or mental mesotonia in contrast to the more physically active mesotonia of the extraverted thinking type. He does not boom out vocally or try to dominate a social situation, but he has an inner hardheadedness and mental drive, and it can produce through the inferior feeling function a disregard and callousness or obliviousness to the feelings of others that mirrors in its own way the inferior feeling of the mesotonic.

The introverted feeling intuition type differs from the introverted thinking intuition type much like the extraverted thinking type differs from the extraverted feeling type. The traits due to introversion remain in place, like love of privacy, etc., but the character of the mesotonia changes to a more feminine one without the same ruthlessness that comes from feeling in the fourth place. The introverted feeling intuition type can sometimes appear somewhat lifeless because the feelings are not immediately visible.

The introverted thinking sensation type and the introverted feeling sensation type can be mistaken at first glance for more or less amiable extraverted sensation types. Despite appearances they possess little of the sociophilia and smooth extraversion of feeling that is the hallmark of the endotonic. They share with the rest of the ectotonics a certain distinctive self-conscious movement of the eyes. It is almost as if they are introverts in extraverted bodies.

The introverted thinking sensation type can be a businessman with a difference. He has the mental equipment to pay attention to practical detail combined with the introvert's instinct for preservation. Add to this a love of competition and dominating and a dash of ruthlessness that comes from the mesotonia and it can be a formidable combination for material success.