Among the five elements there exist the relations of promotion, restriction (interaction), subjugation (over action), and reverse restriction (counteraction).

Promotion implies promoting growth. The order of promotion is as follows: wood promotes fire, fire promotes earth, earth promotes metal, metal promotes water, and water, in turn, promotes wood. As far as the relationship of generation of each of the five elements is concerned, it is composed of two aspects-promoting and being promoted. The element that promotes is called the mother, while the element that is promoted is called the son. Hence, the relation of promoting and being promoted among the five elements is also known as that of "mother and son". Take fire for example. Because fire produces earth, it is called the mother of earth. On the other hand it is produced by wood, so it is called the son of wood.

Restriction means bringing under control or restraint. So far as the relationship of restriction that the five elements process is concerned, it works in the following order: wood restricts earth, earth water, water fire, fire metal, and metal wood. Each of the five elements has the chance of restricting and being restricted. Take fire for example. The element restricting fire is water, and element that is restricted by fire is metal.

In view of the co-relations among things, neither promotion nor restriction is dispensable. Without promotion, there would be no birth and development; without restriction excessive growth would result in harm. For instance, on one hand, fire promotes earth, and on the other, it restricts metal; while metal, in return, promotes water and restricts wood. Thus in promotion there resides restriction, and in the restriction there exist promotion. They oppose each other and at the same time cooperate with each other, thus a relative balance is maintained between promotion and restriction, and the normal growth and development of things is ensured.

Should one of the five elements be excessive or insufficient, there would appear the phenomena of abnormal restrictions, known as subjugation and reverse restriction. By subjugation is meant that one element subduces the other when the latter is weak. It is the manifestation of abnormal coordination among things. For example, if wood is in excess and metal cannot exercise normal restriction on it, then the excessive wood will subjugate earth in such a way that earth will become weaker.

Reverse restriction means preying upon others. That is, when anyone of five elements is in excess, the one originally restricting it will be restricted by it instead. That is why we call it reverse restriction. For instance, the normal order of restriction is that metal restricts wood; but if wood is in excess or metal is insufficient, wood will restrict metal in the reverse direction. It is clear that the order of reverse restriction is just opposite of that of restriction and that reverse restriction is undoubtedly a harmful one. Abnormal promotion will lead to conditions called "Mother affecting the Son" or "Son affecting the mother". For example, normally water promotes wood; in abnormal conditions water will affect wood (Mother affecting Son) or wood will affect water (Son affecting Mother).