Keep thy heart with all diligence; for out of it are the issues of life. Proverbs 4:23.
Diligent heart-keeping is essential to a healthy growth in grace. The heart in its natural state is a habitation for unholy thoughts and sinful passions. When brought into subjection to Christ, it must be cleansed by the Spirit from all defilement. This cannot be done without the consent of the individual.
When the soul has been cleansed, it is the duty of the Christian to keep it undefiled. Many seem to think that the religion of Christ does not call for the abandonment of daily sins, the breaking loose from habits which have held the soul in bondage. They renounce some things condemned by the conscience, but they fail to represent Christ in the daily life. They do not bring Christlikeness into the home. They do not show a thoughtful care in their choice of words. Too often, fretful, impatient words are spoken, words which stir the worst passions of the human heart. Such ones need the abiding presence of Christ in the soul. Only in His strength can they keep guard over the words and actions....
Many seem to begrudge moments spent in meditation, and the searching of the Scriptures, and prayer, as though the time thus occupied was lost. I wish you could all view these things in the light God would have you for you would then make the kingdom of heaven of the first importance. To keep your heart in heaven will give vigor to all your graces, and put life into all your duties.... As exercise increases the appetite, and gives strength and healthy vigor to the body, so will devotional exercises bring an increase of grace and spiritual vigor....
Let the prayer go up to God, “Create in me a clean heart” (Psalm 51:10); for a pure, cleansed soul has Christ abiding therein, and out of the abundance of the heart are the issues of life. The human will is to be yielded to Christ. Instead of passing on, closing the heart in selfishness, there is need of opening the heart to the sweet influences of the Spirit of God. Practical religion breathes its fragrance everywhere. It is a savor of life unto life.33SDA Bible Commentary 3:1157.
From God's Amazing Grace - Page 295
God's Amazing Grace