Nor has any ulterior motive we may have in telling an untruth the power to change its nature; a lie is a lie, no matter what prompted it.  Whether it serves the purpose of amusement, as a jocose lie; or helps to gain us an advantage or get us out of trouble, as an officious lie; or injures another in any way, as a pernicious lie:  mendacity is the character of our utterances, the guilt of willful falsehood is on our soul.  A restriction should, however, be made in favor of the jocose lie; it ceases to be a lie when the mind of the speaker is open to all who listen and his narration or statement may be likened to those fables and myths and fairy tales in which is exemplified the charm of figurative language.  When a person says what is false and is convinced that all who hear him know it is false, the contradiction between his mind and its expression is said to be material, and not formal; and in this the essence of a lie does not consist.

A lie is always a sin; it is what is called an intrinsic evil and is therefore always wrong.  And why is this?  Because speech was given us to express our thoughts; to use this faculty therefore for a contrary purpose is against its nature, against a law of our being, and this is evil.  The obnoxious consequences of falsehood, as it is patent to all, constitute an evil for which falsehood is responsible.  But deception, one of those consequences, is not in itself and essentially, a moral fault.  Deception, if not practised by lying and therefore not intended but simply suffered to occur, and if there be grave reason for resorting to this means of defense, cannot be put down as a thing offensive to God or unjustly prejudicial to the neighbor.  But when deception is the effect of mendacity, it assumes a character of malice that deserves the reprobation of man as it is condemned by God.  And this is another reason why lying is essentially an evil thing, and can never, under any circumstances be allowed or justified.

This does not mean that lying is always a mortal sin.  In fact, it is oftener venial than mortal.  It becomes a serious fault only in the event of another malice being added to it.  Thus, if I lie to one who has a right to know the truth and for grave reasons; if the mendacious information I impart is of a nature to mislead one into injury or loss, and this thing I do maliciously; or if my lying is directly disparaging to another; in these cases there is grave malice and serious guilt.  But if there is no injustice resulting from a lie, I prevaricate against right in lying, but my sin is not a serious offense.