The spirit mingled with the body and brought forth the soul. As such, man became a living soul. Hence, the soul is the result of the union between the spirit and the body; it is the personality of a man.
The body is the outer shell of the soul, and the soul is the outer shell of the spirit. Before man fell, it was the spirit that controlled his entire being. When the spirit wants to do something, it communicates this to the soul, and the soul motivates the body to obey the command of the spirit. This is the meaning of the soul as the medium. Luke 1:46-47 says, "My soul magnifies [present tense] the Lord, and my spirit has exulted [perfect tense] in God my Savior." The spirit must first exult, before the soul can magnify the Lord. The spirit first communicates the exultation to the soul, then the soul communicates to the body.
The body is the "world-consciousness," the soul is the "self-consciousness," and the spirit is the "God-consciousness." There are five organs in the body, which afford man the five senses. This physical body enables man to communicate with the physical world. This is why it is called the "world- consciousness." The soul includes that part known as man’s intellect, which helps to make man’s existence possible. The part of love generates affections toward other human beings or objects. The part that can be aroused is the part that originates from the consciousness. All these are parts of the man himself; they form the personality of man. Hence, they are called the "self-consciousness." The spirit is the part with which man communicates with God. With this part, man worships God, serves Him, and understands his relationship with God. Hence, it is called the "God-consciousness."
The spirit has knowledge, but this knowledge is different from the knowledge of the mind. Because the spirit is different from the mind, only a spiritual man can know himself. First Corinthians 2:11 says, "For who among men knows the things of man, except the spirit of man which is in him?" Although man knows things through the mind, his mind is actually not trustworthy and cannot know "the things of man." The mind may have knowledge, but only by man’s spirit can he know the things of man and know himself. Hence, God’s Word states the fact: "For who..knows the things of man, except the spirit." This spirit is the part with which man fellowships with God. "But there is a spirit in man: and the inspiration of the Almighty giveth them understanding" (Job 32:8). "The spirit of man is the candle of the Lord, searching all the inward parts of the belly" (Prov. 20:27). The spirit of man is the part with which man fellowships with God.
The soul can be stimulated, and it can be disquieted (Psa. 42:5). It can feel sorrowful (Matt. 26:38). In short, the soul is everything that the personality entails. Hence, we can say that the soul is the personality. Many portions in the Bible do not call man a man, but a soul. For example, when the house of Jacob went down to Egypt, there were seventy people (Gen. 46:27). But the Bible says, "All the souls...were threescore and six" (Gen. 46:26).
The body is like a servant; it is under man’s control.
The soul is the meeting point; here the spirit and the body join. Man communicates with the spiritual realm through the spirit. He communicates with the world of senses through the body. The soul is in between. On the one hand, it communicates with the spiritual realm through the spirit, and on the other hand, it communicates with the physical world through the body.
The soul is in between the spirit and the body; it binds the spirit and the body together as one. The spirit rules over the body through the soul and subjects it under God’s power. The body can induce the spirit to love the world through the soul.
In conclusion, the soul is the source of the personality; man’s judgment, intellect, and love all are of the soul. The spirit is the part with which man communicates with the spiritual realm. The body is the part with which man communicates with the physical realm. The soul is in the middle of these two parts. It exercises its judgment to determine if the spiritual realm is to rule or if the physical realm is to rule. Sometimes the soul rules through its intellect and stimulations; this becomes the rule of the psychological world. Unless the soul yields its rule to the spirit, the spirit cannot rule. Hence, the soul has to authorize the spirit to rule before the latter can rule over the soul and the body. The reason for this is that the soul is the origin of the personality.
(Collected Works of Watchman Nee, The (Set 1) Vol. 01: The Christian Life and Warfare, Chapter 5, by Watchman Nee)