The study of the Yijing, or I Ching (Book of Changes), is an important tradition within Chinese philosophy. At its heart is a way of understanding change through three related meanings of Yi: change, constancy and simplicity. Together, they explain how a world in continual transformation can also display enduring patterns, and how those patterns can be understood.
This article follows the perspective of traditional classical scholarship. It traces the development of Yi from a concrete image to a philosophical idea, explains the relationship between substance and function, and uses the traditional Bazi system to show how this framework is applied.
From a natural image to a philosophy of change
The lizard in the traditional account of Yi
A characteristic approach in early Chinese thought was to draw images from the human body and the surrounding world. The Shuowen Jiezi, an early dictionary of Chinese characters, identifies Yi with a lizard or gecko and describes the character as a pictograph. In the traditional account followed here, the animal's adaptation to changes in light and temperature, expressed through changes in coloration, provides an image of responsiveness to external conditions.
This account connects a concrete natural image with broader meanings of alteration, movement and transformation. It illustrates a familiar pattern in Chinese philosophy: observing things, forming images from them, and using those images to express ideas. Through observation, comparison and abstraction, a particular phenomenon becomes a way of thinking about the wider world.
Yi as continuous generation
The Xici, or Appended Statements, in the Yizhuan (Commentary on the Changes) expresses the philosophical meaning of Yi in the phrase “Continuous generation is called Yi.” Here, Yi extends beyond the image of an animal to describe the ceaseless emergence and transformation of things between Heaven and Earth.
Nothing remains fixed. The movements of the sun and moon, the succession of the seasons, and the birth and death of plants and animals all reveal recurring patterns of transformation. So do the changing fortunes of human life and society. Heat gives way to cold, day to night, and flourishing to decline. Within this tradition, these are manifestations of the same principles of change.
Yi thus offers a general framework for understanding the world. Its scope includes the waxing and waning of qi, the vital activity described in traditional Chinese cosmology; the emergence and dissolution of natural forms; and the rise and fall of human affairs. The aim is to understand the patterns running through these different kinds of transformation.
Three meanings within one framework
The classical roots of the three meanings
The Han-dynasty Yiwei Qianzaodu presents Yi as one name containing three meanings, a teaching developed in later scholarship as change, simplicity and constancy. These meanings form a connected whole rather than three separate ideas.
The interpretation developed here brings them together as constancy as substance, change as function, and simplicity as method. “Substance” means the underlying ground or basis of things; “function” means its active expression. Simplicity is the method through which their relationship becomes intelligible.
Change as the observable condition of things
Change describes the world as we encounter it. Heaven and Earth are in continual motion, and all things undergo transformation. No particular form or material arrangement remains fixed forever. The turning seasons, the changing length of day and night, the growth and decline of living things, and the shifts in human affairs all make this visible.
Philosophically, this challenges the habit of treating things as static and self-contained. The cosmos is understood as an interconnected whole whose balance is dynamic. In the substance and function framework, change belongs to function: it is the visible activity through which underlying principles take effect.
Constancy as the enduring ground of change
Constancy refers to the fundamental principles understood to persist through transformation. Forms and circumstances vary, yet the patterns governing their development are held to endure. Traditional examples include the cyclical waxing and waning of yin and yang; the generating, restraining and regulating relationships of the Five Phases, also commonly called the Five Elements; the interdependence of movement and stillness; and the rising, falling, entering and leaving of qi.
From this perspective, constancy belongs to substance: it provides the underlying basis of things. Change is its outward expression, while constancy is the ground that gives change its order. The traditional saying that countless changes never depart from their source captures this relationship. What endures and what changes are understood through one another.
Simplicity as a method for understanding complexity
Simplicity concerns how we come to understand the Way of Heaven and Earth. Nature and society present an immense variety of appearances, but their underlying patterns are understood to be comparatively simple. The task is to recognize those patterns without becoming lost in the detail.
The classical idea that simplicity makes the principles of the world accessible expresses this approach. Thinkers sought to draw general patterns from complex transformations, making them available for understanding, inference and examination. Grasping the root provides a way to make sense of the branches.
Simplicity therefore operates at the level of method. It does not constitute a third kind of substance or function. Instead, it works across both, helping us recognize the enduring basis of things and follow its changing expressions.
Bazi as a traditional application
The principles of Yi are intended to guide interpretation as well as philosophical reflection. Constancy as substance, change as function, and simplicity as method offer a way to examine both the condition of things and the course of their development. The traditional Bazi, or Eight Characters, system provides an example.
In Bazi theory, the configuration of qi at birth is recorded in an original natal chart, known as the yuanju. The chart represents a person's innate endowment and underlying temperament. Because it is treated as relatively stable, it corresponds to constancy as substance.
Major fortune cycles, known as dayun, and annual cycles, known as liunian, represent changing conditions over time. In this system, shifts in the activity of qi are interpreted as bringing different circumstances and developments at successive stages of life. These ongoing changes correspond to change as function.
The natal basis and later developments are read in relation to one another. Their common ground lies in enduring principles, while their expression unfolds through changing circumstances. This illustrates the traditional idea that the manifest and the subtle form an unbroken continuum. Using yin and yang and the Five Phases to organize complex life circumstances, in turn, exemplifies simplicity as method.
Understanding what changes and what endures
The dialectical thinking of Yi brings together several central concerns of traditional Chinese philosophy. Constancy provides a basis for recognizing enduring principles amid shifting circumstances. Change directs attention to the movement of things and the need to respond to it. Simplicity offers a way to move through complexity toward the patterns that make it intelligible.
Taken together, these three meanings invite us to understand transformation in relation to its ground, and to use clear principles to interpret a changing world.
Frequently asked questions
What does Yi mean in Chinese philosophy?
Yi refers to change and transformation as a way of understanding the world. In the I Ching tradition discussed here, it also encompasses constancy and simplicity. Together, these meanings explain how change can unfold through enduring patterns and how those patterns can be understood.
What are the three meanings of Yi?
The three meanings are change, constancy and simplicity. Change describes the movement of phenomena; constancy refers to the enduring principles underlying that movement; and simplicity is the method used to make complex phenomena intelligible.
How does Bazi relate to I Ching philosophy?
Bazi applies a traditional Chinese cosmological framework involving time, qi, yin and yang, and the Five Phases. In this article, its relatively stable natal chart and changing temporal cycles illustrate the relationship between substance and function. Its use of a concise framework to interpret complex circumstances illustrates simplicity as method.