The prescriptions of the natural law. While the object of natural law is the whole moral order as knowable by human reason, three different levels are regularly distinguished according to the ease with which the obligations of the law can be recognized. Primary precepts are most easily perceived, as for example that good must be done and evil must be avoided. Secondary precepts are also available to most people, such as the prescriptions of the Decalogue. More refined conclusions from the primary and secondary precepts are also attainable by reason but with varying degrees of difficulty, such as the evil of contraception or the fact that direct abortion is always forbidden.