Light and Heat: Edwards on Preaching

"If a minister has light without heat, and entertains his auditory with learned discourses, without a savour of the power of godliness, or any appearance of fervency of spirit, and zeal for God and the good of souls, he may gratify itching ears, and fill the heads of his people with empty notions; but it will not be very likely to reach their hearts, or save their souls. And if, on the other hand, he be driven on with a fierce and intemperate zeal, and vehement heat, without light, he will be likely to kindle the like unhallowed flame in his people, and to fire their corrupt passions and affections; but will make them never the better, nor lead them a step towards heaven, but drive them apace the other way." J. Edwards