Prayer is of three sorts. The one is perpetual: it is holy perpetual desire, which prays in the sight of God…  for this desire directs all thy works, spiritual and corporal, to His honor, and therefore it is called perpetual…The other kind is vocal prayer, when the offices or other prayers are said aloud. This is ordained to reach the third – that is, mental prayer: your soul reaches this when it uses vocal prayer in prudence and humility, so that while the tongue speaks the heart is not far from God… And whenever one felt one’s mind to be visited by God, so that it was drawn to think of its Creator in any wise, it ought to abandon vocal prayer, and to fix its mind with the force of love upon that wherein it sees God visit it.

–Saint Catherine of Siena  (1347-1380)