new life, demonstrates a morally inseparable connection between these two functions. The authority of the Magisterium (teaching authority of the Church and those who hold the office) to interpret the divine intention (in this context, through the structure of the body), is emphasized. Although not all of the Church's teachings on sexuality are present in a literal reading of the biblical text, John Paul gives examples of how they are part of longstanding Church tradition — a tradition that was created in the context of scriptural teachings. The ability of the human body to express truth through the sexual union of married couples is acclaimed. The moral wrongness of using artificial means to manipulate such a significant aspect of the created body is explained. Dominion over outside forces, and also self-mastery through discipline, are integral human drives. However, the language expressed by bodies, in this context the language expressed during sexual intercourse, is so damaged by the use of artificial contraception that the conjugal act "ceases to be an act of love... [or] communion of persons" but rather is a mere bodily union. On the other hand, the licitness of natural family planning (NFP) methods is held to be evident from the structure of the human body, which has natural periods of fertility and infertility. The morality of these methods was literally designed into the body, and use of them, unlike use of artificial contraception, can actually improve the dialog between couples which is expressed through the language of the body. Throughout these speeches the main emphasis is on the intrinsic goodness of the marital act. The power of love between spouses is said to both lead to and be nourished by the moral use of the conjugal act. Thus, moral exercise of sexual intercourse uses the form of the body to reveal the love of God toward Creation. While following the rules of NFP does not guarantee a truly spiritual sexual relationship between husband and wife, understanding the theology that makes NFP acceptable can foster the maturity needed by the couple to attain that level of spirituality, living life by the Holy Spirit. Also, Pope John Paul II warns couples against "lowering the number of births in their family below the morally correct level." Responsible parenthood is greatly encouraged, however it is emphasized that while this sometimes means limiting family size, responsible parenthood can also mandate couples to increase