But still there is more: there is scarcely in the world anything which is more able to turn or bend this way and that the morals of men, as Plato prudently considered it. And in fact, we find by experience that it has a sacred and almost incredible power to move hearts in one way or another. Therefore we ought to be even more diligent in regulating it in such a way that it shall be useful to us and in no way pernicious. For this reason the ancient doctors of the Church complain frequently of this, that the people of their times were addicted to dishonest and shameless songs, which not without cause they referred to and called mortal and Satanic poison for corrupting the world. Moreover, in speaking now of music, I understand two parts: namely the letter, or subject and matter; secondly, the song, or the melody. It is true that every bad word (as St. Paul has said) perverts good manner, but when the melody is with it, it pierces the heart much more strongly, and enters into it; in a like manner as through a funnel, the wine is poured into the vessel; so also the venom and the corruption is distilled to the depths of the heart by the melody....From Preface to the Genevan Psalter, this l0th of June, 1543