Saint Frank and His Nonexistent Creatures

From the First and Second Lives of Saint Francis by Thomas of Celano:

Both Francis and his companions agree in reporting that, when he had spoken thus, the birds exulted marvelously in their own fashion, stretching their necks, extending their wings, opening their mouths, and gazing at him. Francis walked into their midst, touching their heads and bodies with his tunic. Finally he blessed them and, making the sign of the cross, gave them permission to fly off to some other place.

Rejoicing, the blessed father went off with his companions, giving thanks to God whom all creatures worship. Since he had now been made simple by grace and not by nature, he began to accuse himself of negligence for not having preached to the birds before, since they listened to the word of God with such reverence. And thus it came about that, from that day on, he exhorted all birds, all animals, all reptiles, and even nonexistent creatures to praise and love the creator, for every day, when the name of the savior was announced, he himself saw their obedience.