The humanizing character [of NFP methods] is all the more obvious from the fact that using them requires and strengthens the harmony of the married couple, it helps and confirms the rediscovery of the marvellous gift of parenthood, it involves respect for nature and demands the responsibility of the individuals. According to many authoritative opinions, they also foster more completely that human ecology which is the harmony between the demands of nature and personal behaviour.
Pope St. John Paul II, Address to NFP Teachers, 7 December 1996