Of Prayer, by John Calvin, tr. Henry Beveridge [1845], at sacred-texts.com
Let the first rule of right prayer then be, to have our heart and mind framed as becomes those who are entering into converse with God. This we shall accomplish in regard to the mind, if, laying aside carnal thoughts and cares which might interfere with the direct and pure contemplation of God, it not only be wholly intent on prayer, but also, as far as possible, be borne and raised above itself. I do not here insist on a mind so disengaged as to feel none of the gnawings of anxiety; on the contrary, it is by much anxiety that the fervour of prayer is inflamed. Thus we see that the holy servants of God betray great anguish, not to say solicitude, when they cause the voice of complaint to ascend to the Lord from the deep abyss and the jaws of death. What I say is, that all foreign and extraneous cares must be dispelled by which the mind might be driven to and fro in vague suspense, be drawn down from heaven, and kept grovelling on the earth. When I say it must be raised above itself, I mean that it must not bring into the presence of God any of those things which our blind and stupid reason is wont to devise, nor keep itself confined within the little measure of its own vanity, but rise to a purity worthy of God.