A Letter of John Newton On the Snares and Difficulties Attending the Ministry of the Gospel:
If opposition has hurt many, popularity has wounded more. To say the truth, I am in some pain for you. Your natural abilities are considerable; you have been diligent in your studies; your zeal is warm and your spirit is lively. With these advantages, I expect to see you a popular preacher. The more you are so, the greater will your field of usefulness be: but, alas! you cannot yet know to what it will expose you.
It is like walking on ice. When you shall see an attentive congregation hanging upon your words: when you shall hear the well-meant, but often injudicious commendations, of those to whom the Lord shall make you useful: when you shall find, upon an intimation of your preaching in a strange place, people thronging from all parts to hear you, how will your heart feel? It is easy for me to advise you to be humble, and for you to acknowledge the propriety of the advice; but while human nature remains in its present state, there will be almost the same connexion between popularity and pride, as between fire and gunpowder: they cannot meet without an explosion, at least not unless the gunpowder is kept very damp. So, unless the Lord is constantly moistening our hearts (If I may so speak) by the influence of his Spirit, popularity will soon set us in a blaze.
...Beware, my friend, of mistaking the ready exercise of gifts for the exercise of grace.