"It is a most irrational thing to converse with God without an heart...he delights more in the chirping of birds than in the singing of psalms without understanding; for these do what they can and so are accepted; but brutish service from a reasonable creature is intolerable.
Is it reasonable that you should cry out for the Spirit, and think on the flesh? To be hearing about another world and ruminating on this? Your eyes directed to heaven, and your heart in the ends of the earth? The tongue busy, and the soul idle? The knee devout and the thoughts loose? There is no coherence, no reason in this.
Consider, that else thou art a madman before God, and God hath no need of madmen; if one should come to thee about business of life and death, and after a word or two therein should run from one impertinent thing to another, would you not think him mad? If thy thy thoughts were put into words and mingled with thy prayers, what strange mad prayers would they be?"
Quotes from pgs. 36-38 of
A Remedy for Wandering Thoughts in Worship
by Richard Steele
(From Sprinkle Publications, one of my favorite publishers)