Every day, we use one of the most familiar words: “I.”

I am hungry. I am happy. I am angry. I want to go. I am unwilling. I regret it.

Yet if we seriously ask, “Who exactly is this ‘I’?” many people find themselves unable to answer.

We can see our bodies in a mirror. Medicine can observe our organs, cells, and nervous system. Yet when we say “my body,” “my brain,” or “my hand,” language itself already points to something important: the body and the brain belong to “me.” Then who is this “I” that possesses the body and the brain?

The Bible has never understood a human being as merely a physical body.

Paul says, “May your spirit, soul, and body be kept blameless.” Here, spirit, soul, and body are presented separately. The body is the part of a person that can be seen, touched, and measured. The soul is the living subject that can say “I”—the one capable of thinking, feeling, judging, choosing, and taking responsibility. The human spirit is the part that relates to God, the Holy Spirit, and spiritual life.

Today, we also know something very important that people in ancient times did not know: human thoughts, feelings, memories, language, and physical actions must all operate through the nervous system.

Therefore, a human being can be understood through four interconnected dimensions.

The body is the physical structure through which a person lives in this world. The nervous system is the operating system that controls and connects the body. The soul is the subject that can say “I,” think, and choose. The spirit is the living existence through which a person enters into a spiritual relationship with God.

These parts are not assembled together without any relationship to one another. Together, they constitute a living human being.

The body can be compared to a car, and the nervous system to its control system. But the one who actually decides where the car will go is the driver. A person remains who he is not merely because his skin, bones, and organs are still there, but because the “I” possessing self-awareness, memory, emotion, and the ability to choose is still operating.

After a person dies, the body may remain intact for a short time, and the brain tissue does not immediately disappear. Yet that person no longer speaks, judges, or chooses. From another dimension, the Bible tells us that the person’s spirit and soul depart, while the body returns to dust.

Then where does the Spiritual Perception System fit into this picture?

From birth, the human soul continually learns about the world through the nervous system, establishing its understanding and value system concerning money, family, happiness, success, good, and evil. Human behavior consists of the judgments and choices that the soul makes according to these understandings.

After a person believes in Christ, God’s Word begins to enter the nervous system and form a spiritual network grounded in biblical truth. Once the human spirit is born again, it operates within this spiritual network. I call this neural network, which carries the activity of the human spirit and enables communion with spiritual reality, the “Spiritual Perception System.”

The Chinese term for the Spiritual Perception System is lingjue xitong: ling comes from the word for soul, jue comes from the word for perception, and xitong means system. Together, they form the term “Spiritual Perception System.”

When believers understand their own Spiritual Perception System, many biblical concepts that once seemed vague become clear.

Why can a person’s life change so dramatically after believing in Christ, even though the body remains the same as it was before? Because what truly changes is not the person’s facial features or limbs, but the operation of life within.

Why does an inner struggle arise after a person believes? Because the value system previously established by the soul still exists, while the born-again spirit begins to influence the person’s judgments and behavior through the Spiritual Perception System.

Why does the Bible place such strong emphasis on “guarding your heart”? Because the decisive factor in how a person lives is not how strong the muscles are or how attractive the outward appearance is, but what values within that person’s life govern the nervous system and the body.

Therefore, “Who am I?” is not a pointless philosophical question.

If a person believes that he is merely a physical body seeking pleasure, he will naturally live according to the flesh. But if he understands that he is a life created by God, possessing spirit, soul, and body, then the way he views sin, death, eternal life, and his present life will become entirely different.

The first step in understanding the Spiritual Perception System is not learning a new term. It is learning to understand ourselves anew:

I have a body, but I am not merely a body.

I have a brain, but I am not merely a brain.

Within this body, there is also an “I” who can think, choose, obey or rebel, and who will ultimately bear responsibility for the life I have lived.