Prayer is easy only for beginners and for those who are already Saints. During all the long years in between, it is difficult. Why? Because prayer has the same inner dynamics as love, and love is sweet only in its initial stage, when we first fall in love, and again in its final, mature stage. In between, love is hard work, dogged fidelity, and needs willful commitment beyond what is normally provided by our emotions and our imagination.
It's when I say, "I don't know how to love," and, "I don't know how to pray," that I first begin to understand what love and prayer actually are.
As Rembrandt's life moves toward the shadows of old age, as his success wanes, and the exterior splendor of his life diminishes, he comes more in touch with the immense beauty of the interior life. There he discovers the light that comes from an inner fire that never dies; the fire of love. His art no longer tries to "grasp, conquer, and regulate the visible," but to "transform the visible in the fire of love that comes from his own unique heart."