Often, in fact, when the Scriptures speak about the mouth, they refer to the intimate recesses of the heart, where one approves and determines what will eventually be spoken with the mouth, when one speaks the truth. It follows, then, that anyone who approves a lie is in his heart a liar. A person might not lie in his heart, however, if in saying something that is not in his heart, he does so knowing that what he does is evil, but he does so to avoid a greater evil"at the same time disapproving of both evils. Those who hold this principle say that Scripture, as well, must be understood in this sense when it says, "He who pronounces the truth in his heart." With the heart, in fact, one must always speak the truth"but not always with the lips; for example, if someone is forced, so as to avoid a greater evil, to say with his voice something contrary to what is in his mind." A response in fact cannot be known when it remains hidden from others, who cannot listen to the voice of the heart unless the voice of the body makes it heard. But that voice of the heart does reach the ears of the Spirit of the Lord who, as Scripture says in the text cited, fills the whole earth. In that same portion of Scripture it also speaks about lips, the voice and language; but saying that these are known to the Lord means nothing other than what refers to the heart. Thus, when it is said that a sound "reaches our ears," it means that it is no longer hidden even from human beings. - "On Lying 16.31"