When asked which was “the greatest commandment” of the Law code, Jesus replied: “‘You must love Jehovah your God with your whole heart [Greek: kar·diʹa] and with your whole soul [psy·kheʹ] and with your whole mind [di·a·noiʹa].’ This is the greatest and first commandment. The second, like it, is this, ‘You must love your neighbor as yourself.’ On these two commandments the whole Law hangs, and the Prophets.” (Matthew 22:35-40) Here, the heart is referred to in relation to the mind, showing that it must be “heart” in a figurative sense.

¹⁴ Jesus was there quoting from Deuteronomy 6:5: “And you must love Jehovah your God with all your heart [Hebrew: le·babʹ] and all your soul [neʹphesh] and all your vital force.” Also, from Leviticus 19:18: “And you must love your fellow as yourself. I am Jehovah.” So Jesus ranked those two as the greatest and the next greatest commandments of the Mosaic Law covenant. We today are not under the Mosaic Law, but those fundamental requirements have not gone out of date. We should keep them.

15. (a) What triggers the physical heart, and how does it function? (b) What relation does the physical heart have to the brain and mind?

¹⁵ We know that it is the “spirit of life” that moves the physical heart. (Revelation 11:11; Genesis 7:22) This life force triggers the heart of living flesh so that it pumps the life blood to all parts of the human body, including the brain. Jehovah God said: “The soul [neʹphesh] of every sort of flesh is its blood by the soul in it. Consequently I said to the sons of Israel: ‘You must not eat the blood of any sort of flesh, because the soul of every sort of flesh is its blood.’” (Leviticus 17:14) For the whole body to live, the physical heart must propel the life-sustaining blood to all its parts, whether this circulation of the blood be by means of one’s natural God-given heart, by a heart transplanted from the body of someone else or by an insensitive, nonfleshly, mechanical heart. Thus the blood is pumped to the brain, its thinking faculties are stimulated and the mind functions. It becomes evident, therefore, that the physical heart nourishes the brain by reason of supplying it with the blood containing the active life force, the “spirit of life.” Regardless of whether a person is conscious or not, the heart keeps pumping the blood to the brain and all other parts of the body.

16. (a) According to the Bible, what is the figurative heart? (b) What is required of us in loving Jehovah with ‘all the heart’? (c) How do we love him with all our “mind”?

¹⁶ But let us look beyond the literal heart of living tissue. As used in the Bible, the heart stands for the seat of motivation and also of the emotions. This is the figurative heart, which actually means our innermost self. At 1 Peter 3:4 it is described as “the secret person of the heart” (NW), “the hidden person of the heart” (Revised Standard Version), “your inner self” (New International Version). So it is with ‘all the heart’ that we are under command to love Jehovah God. We are also commanded to love Jehovah God with all our soul, with the whole of our being. This calls upon us to love the one living and true God, the Almighty, with all our vital force, directing all our energies to the doing of the revealed will of God and the full performance of his work during this “conclusion of the system of things.” (Matthew 24:3) In addition to this, there must be a loving of the God of the Bible with all our “mind,” our mental faculties.​—Mark 12:29-31.

17. (a) If we love Jehovah with all our heart and mind, what assurance do we have? (b) According to Philippians 4:7, how will our hearts and minds be affected by the peace of God?

¹⁷ It goes without saying that if we express our love of Jehovah God with all our heart and mind, he will take pleasure in answering our prayers, and this assurance will keep us free from anxiety. We shall enjoy a peace that this turbulent world does not enjoy and cannot understand. Why so? Because, as the apostle Paul assured the beloved Christians in ancient Philippi, Greece, “the peace of God that excels all thought [Greek: noun] will guard your hearts [kar·diʹas] and your mental powers [no·eʹma·ta: “minds,” Authorized Version; RS] by means of Christ Jesus.” (Philippians 4:7) Thus our figurative hearts will not become excited to any hasty wrong motivations and emotional disquietude, and the mental powers or mind will not be confused or twisted. A Christian will keep on pursuing his course according to God’s inspired Bible along with the help of the Leader, Christ Jesus.

3. According to Hebrews 10:15, 16, where does Jehovah write the laws of this covenant?

³ When discussing the new covenant, at Hebrews 10:15, 16, the apostle quotes the prophecy of Jeremiah according to the Greek Septuagint Version and writes: “Moreover, the holy spirit also bears witness to us, for after it has said: ‘“This is the covenant that I shall covenant toward them after those days,” says Jehovah. “I will put my laws in their hearts [kar·diʹas], and in their minds [di·aʹnoi·an] I shall write them.”’”

4. (a) How do the figurative heart and the mind differ? (b) In line with Psalm 119, how do Christians in the new covenant apply heart and mind? (c) When and how did the writing of God’s laws on hearts and minds get started?

⁴ In accordance with the functions of the figurative heart and the mind, the Christians who are brought into the new covenant through Christ the Mediator would love Jehovah’s laws with their hearts, being thus motivated to obey those laws, and they would also tenaciously remember those divine laws. As the psalmist expressed it, “How I do love your law! All day long it is my concern [“my meditation,” Revised Standard Version; Authorized Version].” (Psalm 119:97) The putting of Jehovah’s laws into the figurative hearts of Christ’s disciples and the writing of these upon their minds began to take place on the day of Pentecost of 33 C.E. It was then that the holy spirit was poured out upon the waiting disciples of Jesus Christ and visible “tongues as if of fire” rested above the heads of the 120 disciples and they began to speak in foreign languages that they had not studied and learned. A miracle indeed! As a result of the witness there given to the gathered onlookers, there were 3,000 who got baptized as believers in Jesus as the Christ, or Messiah, and who were taken into the new covenant with him as their Mediator.​—Acts, chapter 2; Joel 2:28-32.

5. Who today have been taken into the new covenant, and what evidence identifies these as “branches”?

⁵ Today, 1,900 years later, there is a remnant of “the Israel of God” whose members give evidence of having been taken into the new covenant, being baptized with the holy spirit. They give evidence of having had the laws of Jehovah God put in their figurative hearts and written upon their minds.