Catholic Encyclopedia, Theological Virtues, FaithFaith is an infused virtue, by which the intellect is perfected by a supernatural light, in virtue of which, under a supernatural movement of the will, it assents firmly to the supernatural truths of Revelation, not on the motive of intrinsic evidence, but on the sole ground of the infallible authority of God revealing. For as man is guided in the attainment of natural happiness by principles of knowledge known by the natural light of reason, so also in the attainment of his supernatural destiny his intellect must be illumined by certain supernatural principles, namely, Divinely revealed truths.