It is the blood of Jesus, applied by the Spirit
There is a perpetual proneness to seek our fruitfulness from anything but a close, spiritual, and constant dealing with the cross of Jesus. But as well might we expect the earth to clothe itself with verdure, or the tree to blossom, and the blossom ripen into fruit, without the sun's genial warmth - as to look for fruitfulness in a regenerate soul, without a constant dealing with the Lord Jesus Christ. For just what the sun is to the kingdom of nature, Jesus the Sun of righteousness is to the kingdom of grace - the blessed source of all its verdure, fragrance, and fruitfulness. Then, let all your expectations be centered here.
No real good can come to you, no healing to your spirit, no fruitfulness to your soul, from a perpetual living upon convictions of sin, legal fears, or transient joys - the Divine life can derive no nourishment from these. But live upon the atoning blood of Jesus - here is the fatness of your soul found. This is that which heals the wound, wins the heart, and hushes to repose every fear of condemnation. This is that which enables a poor sinner to look fully at God - feeling that justice, holiness, truth, and every Divine perfection are on his side.
It is the blood of Jesus, applied by the Spirit - which moistens each fiber of the root of holiness in the soul, and is productive of its fruitfulness. This is that which sends the warm current of life through every part of the regenerate man, quickening the pulse of love, and imparting a healthy and vigorous power to every act of obedience.
And when the spiritual seasons change - for it is not always spring-time with the soul of a child of God; when the summer's sun withers, or the autumnal blast scatters the leaves, and winter's fiercer storm beats upon the smitten bough - then the blood and righteousness of Christ, lived upon, loved, and cherished - will yet sustain the Divine life in the soul, and in due season the spring blossom and the summer fruit shall again appear, proving that the Divine life of a believer is "hid with Christ in God."
Then shall be said of you, as was said of the church by her Beloved: "Look, the winter is past, and the rains are over and gone. The flowers are springing up, the season of singing birds has come, and the cooing of turtledoves fills the air. The fig trees are forming young fruit, and the fragrant grapevines are blossoming. Rise up, My darling! Come away with Me, My fair one!"
Then let your heart respond, "Awake, north wind! Rise up, south wind! Blow on my garden and spread its fragrance all around. Come into Your garden, my Beloved - taste its finest fruits!"