The Wealth of Nations by Part 5 Chapter 1 Page 285

physicians, may safely be entrusted to the liberality of individuals, who are attached to their doctrines, and who find benefit or consolation from their spiritual ministry and assistance. Their industry and vigilance will, no doubt, be whetted by such an additional motive; and their skill in the profession, as well as their address in governing the minds of the people, must receive daily increase from their increasing practice, study, and attention.

“But if we consider the matter more closely, we shall find that this interested diligence of the clergy is what every wise legislator will study to prevent; because in every religion except the true it is highly pernicious, and it has even a natural tendency to pervert the true, by infusing into it a strong mixture of superstition, folly, and delusion.