574. In order that man many tend to his Last End, it is not sufficient that the way be pointed out in a general manner (as is done by the natural and positive laws), but these laws must be applied to each act in particular by the practical reason or conscience, as it passes judgment on the right or wrong of an action in the light of all the circumstances. Art. 1: THE LAW OF CONSCIENCE (_Summa Theologica_, I, q. 79, aa. 11-13.) 575. Definition.--Conscience is an act of judgment on the part of the practical reason deciding by inference from general principles the moral goodness or malice of a particular act. (a) It is an act, and as such it differs from moral knowledge and intellectual virtues, which are not transitory but enduring. Moral understanding (synderesis), by which everyone naturally perceives the truth of general and self-evident principles of morality; moral science, by which the theologian or ethician knows the body of conclusions drawn from moral principles; prudence, by which the virtuous man is able to make right applications of moral rules to individual cases--all these are permanent states and are preparatory to the act of conscience, in which one makes use of one’s knowledge to judge of the lawfulness or unlawfulness of an action in the concrete, as attended by all its circumstances. (b) Conscience is an act of judgment, and thus it differs from the other acts employed by prudence--from counsel about the right means or ways of action, and from command as to their use. Counsel inquires what is the right thing to do, conscience gives the dictate or decision, the moral command moves to action. (c) Conscience is in the reason--that is, it is a subjective guide, and thus it differs from law, which is objective. (d) Conscience is in the practical reason. Unlike other judgments, which are speculative and deal not with action or only with theoretical aspects of action (e.g., the judgment that God is perfect, that the active faculties are distinct from the soul, etc.), conscience is concerned with action from the view-point of its moral exercise. (e) Conscience is the inference from general principles, and thus it differs from moral understanding (synderesis). This latter is a habit by which everyone who is mentally developed is able to perceive without argument that certain more general propositions of morality must be true, such as the axioms of the natural law (see above, 319 sqq.); conscience draws conclusions from those axioms.