But not only is it necessary to avoid irrelevant subjects, but it is also needful not to sacrifice essentials for accidentals in any work of this kind. It is the fault of too many textbooks on Moral Theology to stress controversies, cite authors, and quote opinions, at the expense of the principles and reasons that govern and explain the teaching given. This work eschews that method, and is at pains everywhere, first of all, to lay the foundations on which the superstructure is to be built, namely, the definitions and rules that are presupposed to moral judgments and conclusions. Obviously, this is a more logical way of proceeding, and it consequently enables the student much more easily to understand and retain the matter studied, since he can thus reason questions out for himself. Moreover, such a method makes for brevity and renders it possible, as said above, to treat more subjects than could otherwise be treated; it makes it possible to condense the matter of many pages of larger and less accessible works into brief and terse paragraphs. But from this it should not be gathered that the work which follows aims to present Moral Theology in a dryly scientific fashion. On the contrary, it has been our endeavor to treat the matter in a way that is at once clear, solid, comprehensive and interesting. Since the general and the abstract do not make the same strong impression as the particular and the concrete, laws and axioms are copiously illustrated throughout with pertinent and practical examples that often amount to brief _casus conscientiae_, thus combining the theory and the practice of Moral Theology.