Book excerpt: The Catechism of Catholic Ethics is a comprehensive explanation of Roman Catholic teaching on the basic principles of ethics, including: the eternal moral law, natural law, the three fonts of morality, the principle of double effect, the principle of cooperation with evil, the use of personal judgment and conscience, moral certitude, temptation, and differing degrees of sin and culpability. This book clarifies for the reader the distinction between positive and negative precepts, between interior and exterior acts, between doctrine and discipline, and between imperfection and sin. This work also covers magisterial teachings on specific types of acts, including: lying, theft, murder, just and unjust violence, slavery, just and unjust war, abortion, contraception, in vitro fertilization, sexual sins and marital sexual ethics. The book closes with a long chapter on Catholic salvation theology, called grace and salvation.