In a letter to Eberhard Bethge, whose thoughts were preoccupied with love for his wife during military service, Dietrich Bonhoeffer offered some brilliant advice:
[T]here is a danger, in any passionate erotic love, that through it you may lose what I’d like to call the polyphony of life. What I mean is that God, the Eternal, wants to be loved with our whole heart, not to be the detriment of earthly love or to diminish it, but as a sort of cantus firmus to which the other voices of life resound in counterpoint. One of these contrapuntal themes, which keep their full independence but are still related to the cantus firmus, is earthly love. Even in the Bible there is the Song of Solomon, and you really can’t imagine a hotter, more sensual, and glowing love than the one spoken of here (ch. 7:6!). It’s really good that this is in the Bible, contradicting all those who think being Christian is about tempering one’s passions (where is there any such tempering in the Old Testament?). Where the cantus firmus is clear and distinct, a counterpoint can develop as mightily as it wants. The two are “undivided and yet distinct,” as the Definition of Chalcedon says, like the divine and human natures in Christ. Is that perhaps why we are so at home with polyphony in music, why it is important to us, because it is the musical image of the christological fact and thus also our vita christiana? This idea came to me only after your visit yesterday. Do you understand what I mean? I wanted to ask you to let the cantus firmus be heard clearly in your being together; only then will it sound complete and full, and the counterpoint will always know that it is being carried and can’t get out of tune or be cut adrift, while remaining itself and complete in itself. Only this polyphony gives your life wholeness, and you know that no disaster can befall you as long as the cantus firmus continues.
— Letters & Papers From Prison