Catholicism

Introduction to the Devout Life, Chapter xxx (75)

Some further advice concerning speech.
Let your speech be gentle, frank, sincere, plain, simple, and faithful. Guard against duplicity and deceit; for though it is not good to tell every kind of truth at all times, yet one must never speak against the truth: accustom yourself never knowingly to lie, whether to excuse yourself or otherwise, remembering that God is the God of truth. If you lie inadvertently, and can at once repair your fault by some explanation, do not fail to do so; a true apology has far more grace and force in excusing than a lie.
Although one may sometimes prudently and discreetly disguise and conceal the truth by some artifice of words, this should be practised only in matters of importance, and when the glory and service of God plainly require it; otherwise, such artifices are dangerous: for, as Holy Scripture says, _the Holy Spirit dwelleth not in a heart that is dissembling and double_. There is no better or more desirable subtlety than simplicity. Worldly prudence and the artifices of the flesh belong to the children of this world; but the children of God walk without guile, and have hearts without folds: _He that walketh simply_, says the Wise Man, _walketh surely_; lying, duplicity, and deceit always betoken a weak and base spirit.
Saint Augustine had said, in the fourth book of his Confessions, that his soul and that of his friend were but one soul, and that life was hateful to him since the death of his friend, because he would not live by halves, and yet for that very reason he feared to die, lest his friend should die altogether. Afterwards these words seemed to him too studied and affected, so that he revoked them in the book of his Retractations, and called them an ineptitude. Do you see, Philothea, how sensitive this holy and beautiful soul is to affectation of speech! Indeed, it is a great ornament of the Christian life to speak faithfully, plainly, and sincerely: “I have resolved,” said David, “to take heed to my ways, that I sin not with my tongue. O Lord, set a watch before my mouth, and a door of circumspection at my lips.”
It is a principle of King Saint Louis that one should never contradict anyone, unless there be sin or some great harm in agreeing with him. This is the way to avoid a multitude of contentions and disputes. Now, when it is necessary to contradict others and set one’s opinion against theirs, one must do so with great gentleness and caution, without in any way seeking to force their minds; for indeed, nothing is gained by taking things harshly.
The rule of speaking little, so highly recommended by the ancient sages, is not to be understood as meaning that one must say few words, but that one must not say many useless ones; for, as regards words, it is not their quantity that is considered, but their quality. And it seems to me that we must here avoid two extremes: the first is to act too knowing and severe, refusing to join in the familiar talk that takes place in conversation, because this then seems to show a lack of confidence, or some kind of contempt; the second is always to jest and chatter, leaving others neither the time nor the opportunity to say what they wish, because this bespeaks a flighty and frivolous mind.
Saint Louis did not like people to speak privately and in counsel when in company, especially at table, because this made it seem that they were speaking ill of others: _He_, he would say, _who is at table in good company, and has some jest to tell, should tell it for all to hear; but if it is something of little importance, he should keep it to himself and speak of it to no one._

Source François de Sales, Introduction à la vie dévote (1609), Project Gutenberg #53540 — I Choose Peace translation from the French · Contents