According to the Scriptures, the heart can be troubled, wounded, pierced, grieved, even broken. How well we all know that. Thankfully, it can also be cheerful, glad, merry, joyful, rejoicing. The heart can be whole or divided—as in that phrase we often use, "Well, part of me wants to, but the other part of me doesn't." It can be wise or foolish. It can be steadfast, true, upright, stout, valiant. (All of these descriptions can be found by perusing the listings for the word heart in any concordance.) It can also be frightened, faint, cowardly, melt like wax. The heart can be wandering, forgetful, dull, stubborn, proud, hardened. Wicked and perverse. I think we know that as well.
Much to our surprise, according to Jesus, a heart can also be pure, as in, "Blessed are the pure in heart, for they will see God" (Matt. 5:8). And even noble, as in his story about the sower: "But the seed on good soil stands for those with a noble and good heart, who hear the word, retain it, and by persevering produce a crop" (Luke 8:15). The Bible sees the heart as the source of all creativity, courage, and conviction. It is the source of our faith, our hope, and of course, our love. It is the "wellspring of life" within us (Prov. 4:23), the very essence of our existence, the center of our being, the fount of our life.
There is no escaping the centrality of the heart. God knows that; it's why he made it the central theme of the Bible, just as he placed the physical heart in the center of the human body. The heart is central; to find our lives, we must make it central again.