The first stage in the corruption of morals is the banishment of truth; for, as Pindar said, truthfulness is the beginning of a great virtue, and is the first item that Plato demands of the governor of his Republic. Our truth of today is not what is, but what others can be convinced of; just as we call “money” not only that which is legal, but also any counterfeit that will pass. …
Thus I have often pondered what could be the source of that custom, which we observe so religiously, of feeling more bitterly offended when taxed with this vice, which is so common among us, than with any other; and that it should be the worse insult that can be given us in words, to accuse us of lying. My findings on the matter are that it is natural to defend ourselves most for the defects with which we are most tainted. It seems that in resenting the accusation and growing excited about it, we unburden ourselves to some extent of the fault; if we have it in fact, at least we condemn it in appearance.
Would it not also be that this reproach seems to involve cowardice and lack of courage? Is there any more obvious cowardice than to deny what we have said? Worse yet, to deny what we know?
Lying is an ugly vice, which an ancient depicts in most shameful colors when he says that it equals giving evidence of contempt for God, and at the same time of fear of men. It is not possible to represent more vividly the horror, the vileness, and the unhealthiness of it. For what can you imagine uglier than being a coward toward men and brave toward God? Since mutual understanding is brought about solely by way of words, he who breaks his word betrays human society. It is the only instrument by means of which our wills and thoughts communicate, it is the interpreter of our soul. If it fails us, we have no more hold on each other, no more knowledge of each other. If it deceives us, it breaks up all our intercourse and dissolves all the bonds of our government.
[Michel de Montaigne, Selected Essays; translated by Donald M. Frame (Walter J. Black, 1943).]