The ruling type (Red)

They are, from childhood on, characterised by a tendency to be rather aggressive and dominant over others.

Their energy – the strength of their striving after personal power – is so great that they tend to push over anything or anybody who gets in their way. The most energetic of them are bullies and sadists; somewhat less energetic ones hurt others by hurting themselves, and include alcoholics, drug addicts, and suicides.

The socially useful type (Yellow)

This is the healthy person, one who has both social interest and energy.

Note that without energy, you cannot really have social interest, since you would not be able to actually do anything for anyone!

The leaning type (Green)

They are sensitive people who have developed a shell around themselves which protects them, but they must rely on others to carry them through difficulties in life. They have low energy levels and so become dependent. When overwhelmed, they develop what we typically think of as neurotic symptoms: phobias, obsessions and compulsions, general anxiety, hysteria, amnesias, and so on, depending on individual details of their lifestyle.

The avoiding type (Blue)

These have the lowest levels of energy and only survive by essentially avoiding life — especially other people. When pushed to the limits, they tend to become psychotic, retreating finally into their own personal worlds.

Adler noted that …

Adler noted that his four types looked very much like the four types proposed by the ancient Greeks. They, too, noticed that some people are always sad, others always angry, and so on. But they attributed these temperaments (from the same root as temperature) to the relative presence of four bodily fluids called humors.