God charged man to till the garden that life may grow for the fulfillment of the first aspect of God's purpose, that is, to express God in His image. Tilling the ground was for the growth of the tree of life. What does it mean to till the ground? This matter of tilling the ground was sown as a seed in Genesis 2 and developed in Matthew 13. In Matthew 13 the Lord Jesus says that the ground is the human heart. Furthermore, in Matthew 13 the tree of life is the Lord Jesus Himself as the seed which He sows into our heart. To till the ground means to loosen and break our hard heart, to open our heart to the heavens that rain may descend for the growth of life within us. When God charged man to till the ground, it meant that man had to be open, broken, and prepared for the tree of life to come into him.
Along with this charge, God gave man an order: man must not only till the ground, but also guard it. God warned man to protect the garden from the enemy that the second aspect of His purpose might be fulfilled, that is, to deal with Satan by His authority. The tree of life requires the tilling of the ground, and the tree of knowledge necessitates the guarding of the ground. We need to till the ground that God might be able to enter into us. However, since Satan also wants to invade us, we need to guard the ground, leaving no opening for the tree of knowledge. To till the ground is to open ourselves to the tree of life; to guard the ground is to close ourselves to the tree of knowledge.
Genesis 2:17 tells us that God issued man a warning and gave him a prohibition. God wanted man only to touch Him to receive life, but not to touch the things apart from God to receive death. God seemed to tell Adam and Eve, "Don't touch the tree of knowledge—only touch the tree of life. If you eat the tree of life, you will receive Me and have My life. If you eat the tree of knowledge, you will take in Satan and have his death." This was not merely a commandment; it was a warning. We must realize that in the whole universe there are two sources: one is the source of life, and the other is the source of death. Be careful which source you touch. If you touch God, you have the source of life and receive life. If you touch Satan, you have the source of death and receive death.