"Introduction à la vie dévote" by Saint Francis de Sales is a spiritual guide first published in 1609. Originally compiled from letters of spiritual direction to his cousin navigating piety amid courtly life, it addresses all Christians regardless of vocation. The work presents holiness as accessible to everyone—soldiers, craftsmen, married people—through five parts covering resolution, prayer, virtue, temptation, and spiritual renewal. Distinguished by simple French and imagery from daily life, it became widely popular across Protestant and Catholic circles.