To err is to make a mistake. To be errant is to make a habit of this. Errantry, however, came to mean wandering as a way of living in the positive sense of actively practicing virtue.
In medieval romances, knights-errant wandered the land in search of adventures. They would do this to test their virtue, help others, and glorify their courts. By wandering around, knights knew they would be confronted by unexpected challenges. Would they be resourceful enough to respond creatively? If so, they would witness with clarity to the lord or lady they served. If not, they could still redeem their failure by learning from it.
