J. I. Packer:
Truth obeyed, said the Puritans, will heal. The word fits, because we are all spiritually sick — sick through sin, which is a wasting and killing disease of the heart. The unconverted are sick unto death; those who have come to know Christ and have been born again continue sick, but they are gradually getting better as the work of grace goes on in their lives.
The church, however, is a hospital in which nobody is completely well, and anyone can relapse at any time. Pastors no less than others are weakened by pressure from the world, the flesh, and the devil, with their lures of profit, pleasure, and pride, and, as we shall see more fully in a moment, pastors must acknowledge that they the healers remain sick and wounded and therefore need to apply the medicines of Scripture to themselves as well as to the sheep whom they tend in Christ’s name.
All Christians need Scripture truth as medicine for their souls at every stage, and the making and accepting of applications is the administering and swallowing of it.
J. I. Packer, A Quest for Godliness
, 1990, reprint (Wheaton, IL: Crossway, 2010), 65, paragraphing added.