From a letter by Jonathan Edwards to his 15 year old daughter, Mary, who was visiting family in New Hampshire, written July 26, 1749:
I hope you will maintain a strict and constant watch over yourself and against all temptations: that you don’t forget and forsake God; and particularly that you don’t grow slack in secret religion. Retire often from this vain world, and all its bubbles, empty shadows, and vain amusements, and converse with God alone; and seek that divine grace and comfort, the least drop of which is more worth than all the riches, gaiety, pleasures and entertainments of the whole world.
Posterity: Letters of Great Americans to Their Children, Dorie McCullough Lawson, Doubleday, 2004, pp. 132-33.