Love is not only pure joy, and delight, but also great and deep heaviness of heart and sorrow. But love too is full of joy and sweetness even in bitter sorrow, because it regards the misery and injury of others as its own. So also Christ was glowing with burning love in His last and greatest agony. According to St. Hilary, it was Christ's greatest joy that He endured the greatest woe. Thus God "giveth strength and power unto His people" (Ps. 68:15). While they experience the greatest sorrow, their hearts overflow with joy.
Martin Luther, Commentary on Romans
christ, love, luther