"Methods of observation that enable a couple to determine periods of fertility," he continues, "allow them to administer what the Creator wisely inscribed in human nature without disturbing the integral meaning of sexual relations. In this way the spouses, while respecting the full truth of their love, can modulate the expression thereof in accordance with these rhythms. ... Clearly this requires a maturity in love, ... and mutual respect and dialogue."
The Pope also asks why the world and many faithful are unable to accept a teaching about sexuality that “explains and defends the beauty of conjugal love in its natural expression."
Although "technological solutions to the great human problems often seem the easiest,” the Pope cautions, “in reality they hide the basic problem which concerns the meaning of human sexuality and the need for responsibility so that its exercise may be an expression of personal love."
"Technology cannot substitute, … when love is at stake. Indeed, as we well know, not even reason is enough. ... Only the eyes of the heart can perceive the requirements of a great love capable of embracing the entire truth of human beings," writes the Pope.