Married couples are not saints, and sin is not some error which we may renounce one of these days in order to adopt a more accurate truth. We are unendingly and incessantly in the thick of the struggle between nature and grace; unendingly and incessantly unhappy and then happy. But the horizon has not remained the same. A fidelity maintained in the Name of what does not change as we change will gradually disclose some of its mystery: beyond tragedy another happiness waits. A happiness resembling the old, but no longer belonging to the form of the world, for this new happiness transforms the world.

Denis de Rougemont, Love in the Western World

Nature is said to have required several hundreds of thousands of years for the selection of those species which now seem to us adapted to their surroundings. And yet we have the presumption to suppose that all of a sudden in the course of a single life we may solve the problem of the adaptation to one another of two highly organized physical and moral beings.

Denis de Rougemont, Love in the Western World