Just as our body has many parts, so does our spirit and our soul. Our spirit is composed of three: conscience, fellowship, and intuition. The conscience is for us to discern right from wrong, to justify or to condemn. Romans 9:1 compared with Romans 8:16 proves that the conscience is a part of our spirit. Fellowship is for us to contact God and to commune with God. This is shown in John 4:24 and Romans 1:9. Intuition means to have a direct sense or feeling in our spirit, regardless of reason or circumstance. First Corinthians 2:11 indicates that our spirit can know what our soul cannot. Our soul knows by reason or by circumstance, but our spirit can perceive without these. This is intuition, the direct sense in our spirit.
The soul is also of three parts. The main one, the mind, is for thinking, considering (Psa. 13:2), knowing (Psa. 139:14), and remembering (Lam. 3:20). In the mind we have thoughts, ideas, concepts, reasonings, understanding, knowledge, etc. Emotion, another part of the soul, is for us to love (1 Sam. 18:1; S.S. 1:7) or hate (2 Sam. 5:8), to like or dislike, to be joyful (Isa. 61:10; Psa. 86:4) or grieved (1 Sam. 30:6; Judg. 10:16). All our emotional feelings, positive or negative, are in this part of our soul. The will is also a part of the soul. It is the part through which we have our purposes and choices (Job 7:15; 6:7) and make decisions (1 Chron. 22:19). When I consider or reason, I am using the mind. When I feel happy or sorrowful, I am in the emotion. When I make a decision to do a certain thing, the will is in operation. The mind, the emotion, and the will are the three parts of the soul.
Psalm 51:6 reveals that within our being are "the inward parts" and "the hidden part." Hebrews 8:10 compared with Jeremiah 31:33 proves that the mind is one of "the inward parts." The rest of "the inward parts" must be the emotion and the will. Therefore, all the parts of our soul are "the inward parts" of our being, while our spirit is "the hidden part."
Since 1 Thessalonians 5:23 speaks definitely that we are a tripartite being composed of the spirit, the soul, and the body, the heart could not be a separate part in addition to the spirit and the soul. The heart is a composition of the first part of the spirit and all three parts of the soul. It includes the conscience (Heb. 10:22), the first part of our spirit. Thus, it condemns (1 John 3:20) as does the conscience. It also includes the mind, the will, and the emotion, which are the three parts of our soul. Thus, it thinks (Matt. 9:4) and has thoughts (Gen. 6:5; Heb. 4:12); it rejoices (John 16:22) or has sorrow (John 16:6); and it purposes (Acts 11:23) and has intents (Heb. 4:12). Hence, the Scripture shows us clearly that our heart is composed of the conscience, the mind, the emotion, and the will. It is equal to a part of our spirit and the whole of our soul. Since the heart is thus composed of parts of our spirit and soul, it is very closely related to both.
The purpose of our body is our human existence. It is by our body that we may exist and live physically and practically for the Lord. Our body is for the Lord, and the Lord is for our body (1 Cor. 6:13). The Lord prepares us a body (Heb. 10:5) that we may exist and live for Him. Thus, we must offer our body to the Lord (Rom. 12:1) and glorify Him in our body (1 Cor. 6:20).
The purpose of our heart in God’s intention is that it may love Him. Mark 12:30 says, "Thou shalt love the Lord thy God with all thy heart." Our heart is a loving organ, prepared by God for us to love Him. The purpose of our spirit is to contact the Lord (John 4:24), to receive Him (1 Cor. 6:17), and to contain Him (2 Tim. 4:22). Our heart is the loving organ, whereas our spirit is the contacting, receiving, and containing organ. The Lord whom our heart loves is contacted, received, and contained by our spirit. What then is the purpose of our soul? Its main purpose is to reflect and express the Lord. Second Corinthians 3:18, in the original text, has the thought of reflecting. Our soul, that is our person or our personality, must be the very organ, as a mirror, to reflect and express the Lord. Thus, we love the Lord with our heart; we contact, receive, and contain Him with our spirit; and we reflect and express Him with our soul in all that we think, like, and decide—in all that we are and all that we do.
(The Parts of Man, Chapter 1, by Witness Lee)