The Institutes, Book 7
Not Taking Back What We Have Given Up
If, then, out of desire for perfection you have left everything and followed Christ, who says to you, “Go, sell all that you have and give to the poor, and you will have treasure in heaven; and come, follow me,” why, having put your hand to the plow, do you look back, so that the voice of the same Lord will declare you unfit for the kingdom of heaven? When you stand safe on the housetop of the gospel, why do you come down to carry something out of the house, those very things you once despised? When you are out in the field, working at the virtues, why do you run back and try to clothe yourself again in what belongs to this world, which you stripped off when you renounced it?
But if poverty kept you from having anything to give up, still less ought you to pile up what you never had before. For by the grace of the Lord you were made ready for this very purpose: that you might hurry to him all the more readily, caught in no snares of wealth. Yet no one who lacks possessions should lose heart, for there is no one who has nothing to give up. Whoever has thoroughly rooted out the desire to possess has renounced all the possessions of this world.